Downloading now... going see if the wife will play and hook her on the story :)

Okay, after giving the demo a go, I have to say . . . I can't share the enthusiasm.
The minimal interactivity doesn't bother me that much. I'm a fan of the point-and-click adventures of old, and really, the likes of Monkey Island, Gabriel Knight, and Broken Sword aren't that much more interactive. Hell, Phoenix Wright is 95% reading, 5% picking the right thing from a menu, and those games are delightful.
The main thing that sets games like those apart, though (besides the puzzles), is decent storytelling. Now, it's a bit early to judge the entirety of Heavy Rain's story from a half-hour demo, but based on the bits and pieces I've seen and played, it'll have to be a tour de force to make up for all the rubbish. The voice acting ranges from mediocre to terrible (I swear, every time the prostitute opened her mouth, I was howling with laughter--Shatner would be envious of her delivery), the script is at least three-quarters cobbled together movie/TV thriller leftovers (A Saw homage? Really?) with no sense of how people actually talk to one another, and the animation is inconsistent (sometimes the faces and body movements look all right, sometimes they go into full-on Uncanny Valley mannequin mode). For all the big-budget ambitions--and the game does, for the most part, look impressive--the presentation all too often feels amateurish. And nothing I've seen in any videos outside the demo, from the opening mall scene to the unintentionally hilarious sex scene, shows any improvement on this.
I could see the actual game system working really well with a good story. As far as I can tell, though, David Cage doesn't have that story in him.
For my money, Way of the Samurai for PS2 already did this sort of thing much better (minus the multiple characters). It's extraordinarily rough around the edges, and the story isn't much more than a remake of Yojimbo, but the actual storytelling is solid, and it really gives you the sense of playing an active role in an ever-shifting samurai epic--making a couple of slightly different choices can show you a completely new side of the conflict. Plus, one playthrough's about two hours long (shorter if you die), which feels about perfect pace-wise for this sort of game.
Seriously, whatever your feelings about Heavy Rain, I urge you to give Way of the Samurai 3 (on PS3 and 360) a shot if you're into that sort of interactive storytelling. It's the same sort of experience as the first game, and it does a hell of a lot with a tiny fraction of Heavy Rain's budget.
I'm sorry for the rambling--I get that way from time to time. Tl;dr version: The demo didn't wow me. And Way of the Samurai is awesome.

I just bought a ps3 yesterday whooo. I will dl the demo later

I liked it. Looks great, feels great, the VAs sometime feel lacking, but all in all, not half bad. :)

I'm sort of with paakType. I tried the demo and I didn't like it either, though for completely different reasons. Going into it, I didn't know much about the game other than it was made by the Indigo Prophecy people and that it seemed to be eagerly anticipated by some of ps3 crowd.
I don't know what i was expecting, I just knew it wasn't like your typical console videogame. But gameplay consisting of QTEs and command prompts don't do it for me, and I really disliked the walking controls

I am considering going with a different language with English subtitles, depending on how I feel while playing. It's a French-made game, so why not? But then again, they're all meant to be American. Hmm... why couldn't they just get American people instead of having French people using American accents?

Budget cuts maybe? But it's not that bad.

Greatest Demo I Have Ever played
I Will be buying it what ever it costs no matter what i must do
I will be putting all games to buy on hold untill i have this title.
This may trump Shadows of Colossus as my all time favorite game Ive ever played since i drew breath and plugged in TANK into my Atari 2600
Beyond all doubt anyone that owns a PS3 needs to experience this, if I didn't own one I would BUY one for this game.

The mouth animation needs help.

Gametrailers did a pretty in-depth review of the full game for those who have played the demo and are interested on how the rest of the game is.
http://www.gametrailers.com/video/review-hd-heavy-rain/61847
I'll probably pick it up when it comes down in price.