Dark Souls is an awesome game despite the fact that it has very little multiplayer support.
The RPG aspect of the game is what keeps me going. The fact that you can level your character in the way that you want, obtain some really cool weapons that scale with your stats and roam a completely open world makes this game great. The bosses are incredibly hard. The only boss I defeated on my first try was the moonlight butterfly; every other boss was almost an instant first death. Dark Souls can get a little frustrating, especially when you have a lot of souls on you and decide to venture forth and wind up cut down by some tough enemy you've never seen before, but it doesn't make me want to quit, it makes it more exciting when you finally do get to that next bonfire.
The one thing that sucks about the game is that it lacks multiplayer support. You can't invite your friends to a party otherwise you get put into online mode. If someone does summon you (or vice versa) you cannot hear them. You have a limited number of "gestures" that your character can do to help communicate ideas. You can't invite your friends to your game, the only way you can play co-op is by summoning someone into the game through a white soapstone. Keep in mind Dark Souls has multiple servers and there is no way to choose your server, so you may never play with a friend of yours. The world invasion idea is cool, I just wish there was more cooperation among groups.
Overall the game is awesome, I would recommend it to anybody.