I've seen where it received many poor reviews, but how is it after patches?

Does it offer significantly more content than SEIV?

I'm really enjoying SEIV so far, especially compared to the sort of disappointing Galactic Civilizations II. The flavor text in SEIV is much more detailed and delivered in a more serious manner compared to GCII, which I really appreciate. GCII seems a little empty and less complex by comparison as well.

Desperately seeking something that rivals my enjoyment of Sid Meier's Alpha Centauri...

I haven't played it for a long time but what I remember is that the main differences is the UI and the battles.
The battles are real time and you give orders in various ways that is then executed during battles. Don't remember if you can change anything during the battle.
The UI is, well, not that great I think. I never really got used to it. In fact I think that was what made me ultimately stop playing SE V. But UI is one of those things that some hate and others love so you might like it. Oh and the new map view irritated me to no end.

To put it bluntly: No. Ascendancy was able to handle the whole 3D thing without being attached to a grid and had depth. The game itself is clunky and rather poorly optimized, and I don't recall being able to tolerate the obnoxious flash enough to get very deep into the game.

Changes made in SE V are rather doubtful - pseudo-3D system view and real-time combat. UI is overcomplicated comparing with SE IV, yet icons and pictures (especially race portraits) are quite good. In sum, minor upgrades are overshadowed by major downgrades.
But nonetheless SE V is a very decent game to try. Though it can't be put in the same category that Alpha Centauri, these are very different games despite that both formally are 4X. So in any case your enjoy of Alpha Centauri will stay unchallenged.

In my opinion it is. I think of SE5 as an overall upgrade myself, I don't see why others are nagging. I can do more things with less mouse clicks in SE5. The only part this isn't true is ship design, ships are 3-layer grid layouts where you place parts in certain places and it can be time consuming, some people just dump parts in without caring about placement to save time.

The only negative I have on SE5 is it won't run on Windows 7. I assume this is why we don't see it here on GOG yet.

Yup, I've found out that SE 5 is a very decent game, esp with "captain kwok's balance mod" which allows the AI to not be a complete moron anymore. Many options, a rich diplomatic system, esthetically pleasing... I like it.
Main problem for me is that the UI feels "klunkier" than SE4

A shame it works so poorly on Windows 7 (graphic and audio glitches are painful). It works like a charm under my vista laptop, though.

If they changed it to real-time combat it shows they didn't understand why SE4 was a good game.

He. I like the turn based combat from SE4 too (It's one of the reasons I love MOO2, and I was pleased to find it in SE4). But realtime feels more "fair", somehow. I sometimes feel ashamed of the way I take advantage from the poor tactical AI in SE4 ^^

Seriously, I like the tactical battles in the 2 games. SE5 it feels more like "Fleet command" and less "control each and every ship". The real problem is that the controls are VERY clunky during these battles.

Ascendancy, now that's a game that belongs in GOG...

It has a good amount of votes.

One more now. Thanks!

Yup again, here it is:
http://www.captainkwok.net/balancemod.php

Please tell us how. The mouse for me moves so slowly and lags so much it's unusable, even on my best gaming rig (which is really fast) and the turns take forever to process. I play it on my WinXP box simply because SE5 cannot run right on Win7 for me.

I would if I knew how. :-s
I just have version 1.79 and it's installed from the box.
I installed it and ran it... just works.

Only things I can tell you is I'm running win 7x64(SP1) with a usb mouse + keyboard.
I'm using an nvidia 980Ti (previously 680gtx).
I have resolution set to my current desktop resolution and rendering to hardware T&L HaL.
No windows compatability options are turned on.

Only thing I can think of which might make a difference is that I have legacy usb enabled in my system bios.