I've bought Dark Souls two days ago. Man, what an awesome game. Awesome³, honestly. Probably the best game I've played in years. Hell, I actually think I haven't played anything in the last decade that left as much of an impression on me. You'd have to go back to the SNES days (and me being a kid, which helped to make games seem more impressive ) to find something that could come close.
Being challenged is, for me, a huge part of playing video games and it's something that, I think, games have been lacking for years now. Whether it's Forza, Metal Gear Solid, Elder Scrolls, you name it... Most games make it way too easy to beat them.
I've found Dark Souls to be the exact opposite, and I'm currently regretting that I missed Demon's Souls. I mean, you actualy have to grind a bit here and there to get forward, keep your guard up 95% of the time and actually think before you act. I love that.
It's also a looker, in my opinion. There are some slowdowns here and there, but usually nothing that really throws you of. Add the incredible soundtrack (reminds of older Final Fantasy OSTs, too) and the feeling of loneliness and you've got a brilliant atmosphere. Seems a bit like Vagrant Story, in that regard, which is a very, very good thing.
From Software delivered a master piece and a game that should be considered a modern classic, in my opinion. This is the direction Squaresoft (or SqaureEnix) should have taken there franchises in. For me, at least. A more grown-up design and gameplay to match it. Wouldn't have hurt the Final Fantasy franchise, if you're asking me, if it was a tad more challenging and wasn't riddled with some strange teenage emo-brats