I'm pretty much in the same boat as boiler, I played 1 + 2 and loved them.
I did think the demo was good, but the gameplay didn't make me want to rush out and buy it, I got the impression that it was really just a pretty version of the old games which isn't on the whole a bad thing, but I was left with the feeling that I'd be as well off going back and playing DMC2 on my PS2 as spending $60 on a "pretty version" of the same thing.
I would happily be told that I'm wrong, but I think I'll be dowloading Sid Meier's Pirates from Xbox live on Monday instead of running out to get this.