I plan on getting Demon's Souls as soon as I get some other games on my list (namely FFXIII and Bayonetta).
I saw it in action once, it's so...wildly different to anything I've played. So hazardous. Hardcore even! :D

1. When you die in DS you will lose your body and become a ghost. That will happen. You get your body couple different ways. So what does this mean. In short: when in ghost form your max energy is about half of that when you have your body. So thats a downside. On the other hand you cannot be invaded. Meaning that other players can't come and kill you. So it makes you to do choice. Get your body back and be invadable or go as ghost and die to enemies little easier.
I usually go as ghost cause them bitches kill me alot. When I have honed my ninja skills then I pay back with interest... Usually I "resurrect" my body when I will really try kill some nasty boss demon. Usually ending me diyng on the way there cause mind is on kiling the boss and not normal enemies on the way there. You could resurrect your body with an item just before you enter demons lair. Only to be crushed by that damn tower knight in couple of seconds. Then it's the jog back to the demon as a ghost...
Difficulty is different from Ninja Gaiden. Speed is slower and DS doesn't feel unfair. In Ninja Gaiden you are this superuberninja who kills with his pinkie everything in his path. In DS everything kills you. Well maybe not those starting zombies. Atleast with little leveling.
edit. Online features are either all on, or all off. Nothing in between.

Appreciate the response, Themock.
The reviews mentioned 'always online' and 'passive' elements, so I assumed you could have some elements turned on but not all. Everything's clear now.

Played both but i found Ninja Gaiden 1 a lot harder. Maybe because i'm not good at making some of the advanced combos. :) In Demon's Souls is pretty easy if you're careful to block at the right moment and strike when you know it's safe. The only time i've had trouble at DS was at some stage bosses.

Getting the Black Phantom edition (strategy guide, soundtrack and art book) when it's released. Haven't played it before but the alleged ruthlessnes of the game attracts me to it. Can't wait!

I started playing the game recently and it's not as nearly as hard as I thought it would be.
I'm still very early in the game ( beat the first boss to open up the other levels) so maybe my impressions don't mean much. But I had read a few times that it's pretty difficult in the beginning, and it didn't seem that bad. Yeah I died a lot, but there were shortcuts that opened up to make the routes easier. And I read a comment at gaf that said something like "Oh you WILL die at the first boss" as if it was ridiculously hard, but I beat him on the second try. ( the first time I wasn't even really trying, just testing him out to see what would happen).
You will die, but there are things that make it not infuriatingly difficult ( shortcuts, clues by players on how to defeat enemies, decent amount of heal potions dropped by enemies, items that can't be lost that will give you more souls when you want to use them)
With that said, I want to remind you I am only talking about the first level ( which was supposedly really hard). Once I got passed that part, I got my ass kicked quite a few times on the next level, and I haven't played it for a few days since then . ( Not that the game pissed me off, I was just tired when I quit and I haven't felt like playing anything since then)

But you died on the first boss...;) so he was right. And that blob thingy ain't that hard. Second try also here. Or maybe he mean the one at the of the tutorial.

Yeah actually that does make sense. I forgot about that part of the tutorial.
I'm too lazy to search to see if that's what he was talking about.
Dang now I feel less hardcore for beating the blob boss so easily

I beat "the blob" on my first try. Or as he is called, The Phalanx. It took a lot of time, but once I realized that he and his minions were weak against fire, it was easy. I took my time and killed every minion at first, before going for the big one.
Fantastic game, btw. I'd buy it again if the PAL version was improved in some way, but I've yet to hear of it, so I'll stick to my US copy. It's tough, but it never feels unfair. The beginning was easy for me, because I was so prepared for old school hardcore gameplay. Growing up with old games, I quickly realized that comparing this to old games' difficulty is a slight exaggeration. But it's certainly more difficult than the norm nowadays.

Apparently, though, you can actually beat the tutorial boss if you're insanely good. I've never done it myself, and I have no idea what happens next if you pull it off, but just knowing that it's possible is enough for me.

I got it in February last year

I will definitely be picking this up. It gets released here tomorrow, I'll pick it up on friday. I love the idea. Prepare to be invaded by a Fearsome Viking (tm).

I pre-ordered it at the local Game a month ago. Which probably wasn't necessary, since I was apparently the first one to do it, and, I believe, the only one. Like Stonebro, I will get it on friday.

MIne's processing now from Shopto, so it should get here tomorrow. Definitely Friday anyway (but I'm 99% sure tomorrow). Got it for a bargain price as well, which is why I mentioned the Shopto World Cup competition for others in case they wanted to take part. (Sadly it's going to be harder to get any store credit though soon as you have to guess the scores and not just results.)
I've actually spoilt part of the game for myself sadly by watching Let's Plays of it on Youtube (just the first area). I managed to stop myself from watching anything more, but from what I can make out, even the first couple of normal enemies take off a large chunk of your health when they hit you just once.
Edit: So if I boast about killing the first boss without dying (not the tutorial boss), tell me it doesn't count because I watched a Let's Play. ;)