Well, I haven't played it myself yet...
But from what I'm hearing, D3 is unfortunately not as good as D2...
The changes where too radical from what the series used to be...
The negatives :
- New HoMM3 style combat (no more fixed positions)
- No new units whatsoever (we don't get a new upgrade for all trees) : That's a real shame...
- Only 3 of the 5 factions made it (the 2 left will be coming with the expantions)...
- The art style is pretty bland compared to the one in D2...
- I've heard the maps are extremely linear : you just follow a path that twists and turns in the fog of war, trees and mountains acting like the walls of a maze...
The positives :
- New HoMM3 style combat (no more fixed positions) : some people enjoyed this change, so I'm listing it in both sections...
- The way your hero levels up and has equipment is one of the aspects of D3 people unanimously seemed to like...
- The story and narratives are top notch...
- The price, it's only 40$...
- The graphics (not the art style) are pretty dark and lush...
(- If you get it on Steam, you get 3 extra single player maps, and achievements)
Metacritc score is currently at 62 if you care...
Ok so here is what I think...
As a Disciples fan, I'm buying D3 no questions about it (haven't yet because I'm on vacation)...
The game is good, but it has some issues, and if you can forgive them, you will get sucked in...
If you can't, well you're in for a dissapointment...
Hope this helped make a choice for you :)
Here is the Steam link if you are interested...
It has some screenshots, a trailer, a feature list, plus you can get more opinions from the forums :)
http://store.steampowered.com/app/33670/

Thanks very much for the summary.
I still can't decide :P I think I'll stick around with D2 a liitle bit longer. But I will certainly buy it at some point.

While I haven't played Disciples 3, from most of the customer reviews I've been reading the game is currently in a fairly broken state, and still contains a long list of unpatched bugs. That's in addition to many copies of the US version apparently shipping with numerous key files missing from the disc so that the game can't even be played. General feeling I'm getting is to wait until Akella and Kalypso manage to get their act together, as in maybe a few years.

The best thing you could do is try it out for yourself...
There is a free demo up on Steam :)

I heard a patch has been released yesterday or something like that, solving many bugs in the game.

You know you can just play a demo and make your own decision. I for one hated D3 for all the - reasons DadouXIII listed.

Personally I found disciples 3 rather enjoyable at times, however it is still largely unpolished and some changes really hurt the game:

-The thieves have become a hero-like unit. You still need a thieves guild to hire them, however you'll need to level them up considerably to use they're global (thieving) skills. I really liked the feeling of thieves in the earlier games - they were disposable and could open a lot of options for you via their skills.
-The spells now are a lot less diverse between the races. Each race now has healing (even the legions of the damned), buffing and/or debuffing, damaging and summoning spells. In addition the spell animations feel too long and are shared between different spell tiers. I hope they'll revise the spells with upcoming expansions
-The unit leveling system is bizarre. You cannot lock the unit type(you can only decide not to purchase the upgrade building), even so the 'locked' units only get increased health upon further leveling up - their damage and statistics remain the same.
-The narrator for the game story is really really bad, the story (at least so far - I'm in the 5th elven mission now :) ) is pretty good though.
-There are plenty of bugs (most of the aren't game breaking, but still annoying) and AI is really dumb. Again I hope the upcoming expansions will remedy this.
-No more manual city upgrading, the cities now upgrade automatically.

To the games credit there were some good changes I enjoyed

-The removal of rod planters is a great move, the new node Guardians can protect your area from lower level heroes, especially when reinforced and leveled up.
-You can only cast a single spell during a turn (two if you're a mage lord)
-Runes are an interesting addition, allowing units and heroes to cast spells in combat instead of taking a turn (they cost the same amount of mana and you can make several of them)
-You no longer can move on the water tiles (I really hated how quickly they'd eat your movement points :) )
-I like the fact that they reimagined the looks of all the units, instead of simply porting them from the original game to 3D. Some are better, some are worse but all of them are original :)

In conclusion, I'd recommend to either wait until a steam sale (there should be one before the expansion) or wait until the expansion is released and see whether most of the bugs and complains are fixed.

I have played D3 and have completed the whole game. Personally i didn't like it they spent to much time on making the characters look good then the actual story line. I thought the story line was really crappy and didn't have much to it. For gameplay i would say that it was terrible as well, you have more freedom in D1 and D2 to move around. In D3 there is paths everywhere and you can only follow those paths which i thought was lame. For fighting they have made it more like Heros of might and magic format. The units upgrade the same and they changed the way that the hero upgrades which is hard to explain but i didn't like it.

I'm not a fan of Disciples 3. I like Disciples 1 and 2 both equally, both good games, but Disciples 3 ruined what I liked about Disciples and made it into something else.

As a big Disciples 1 and 2 fan, it's not an improvment for me, but I have some personal history involved with the game development of 3, so it's something I giggle sometimes.

I bought it, I played it.

It's pretty. Very pretty. Perhaps Akella spent entirely too much time making it pretty versus retaining the full amount of charm, style, options and abilities of the 2nd iteration of the series.

They changed a LOT of the formula that I liked, such as not having to worry about unit positioning in favor of focusing on items/potions/builds than strategic positioning. That being said, however, unit positioning is familiar so I don't really count it as a full ding.

Vanilla mode - No Clans, No Undead. That's a problem for me, man. The diversity of factions was one of my most favorite things about Disciples, and the same for the HoMM games as well. I LIKE OPTIONS, STOP LIMITING ME!
You actually have to purchase the expansion in order to get the other two factions that used to be included with the plain jane version of D2. >.<

No Rod Planters. This is good. Babysitting these weaklings was one of my least favorite aspects of the the Disciples games, along with rod/node management. This isn't a ding at all, but a solid decision, imo.

The art style feels generically ripped from things like Hellgate London or Diablo, that's disappointing, considering the artistic feel was previously one of the major draws to Disciples.

All in all? It's not a terrible game. It's a disappointing game that feels like it shouldn't be canon. It feels incomplete, it feels a little "me too," and it loses a lot of its identity in trying to appease ALL audiences of this niche.

Personally, I'd give it a 6.5 of 10.

Disciples: Reincarnation,
It is a complete overhaul of the previous Disciple 3 games (Renaissance & Resurrection) , featuring balanced AI, naval traveling and fighting, etc.
It is as Disciples 3 should have been from the start.

The fact that the Developer went bankrupt a month before official release means that this D3 game went under the radar and sadly under the buss of the mainstream.

It is a true D3 game.

They redone the combat system, the stats, reworked the maps the spells, the added some new units. If you want to play a proper sequel to Disciples 2 this is the one to get, don't even bother with Renaissance and Resurrection.
Too bad they did it too late and now the producer has bitten the dust and we probably won't see any future expansions.

Strategy First developed Disciples 1 + 2, but not 3 and it shows

Renaissance & Resurrection, i got them on bundles for like 30 cents... i think they're not worth it

+Reincarnation it's a complete game, you can play all campaigns
- before Reincarnation, too many games to buy, 1 game 1 campaign for undead.... lame...
- 3 years...
- registration required...
- all the same creatures + tiers from D2, but weird looking, stats changed like a marketing move to cash in the last title...
- crappy interface
-- no random map...
- too boring to get experience to lvl up army...
- archers suck, melee suck with low movement

not much change... in Disciples Reincarnation
Starting with 3 Fiends and kill everything, because of low damage of other creatures / heroes

It is a sad thing but; games are just gonna get prettier and dumber the more time goes on. Prime example is the elder scrolls series... they got simpler and simpler, pretty soon you'd just start up and they'll choose everything for you and you'll never even see how your character is progressing because that is too smart and they feel it would shoo away the masses of the simple minded marketing demographic. Pretty soon I will no longer be able to bother with playing games as they will be beneath myself and most of the real gamers out there that have more than a five second attention-span. Now I just find older games and roms that don't insult my sensibilities with idiotic simplicity.

I almost bought it at a store as a physical copy. Then I saw that it was Steam only and didn't think it was worth the asking price for a permission key.