It isn't "hard," but it does have a difficulty curve which shoots into the stratosphere early on, usually before the player is ready. With the exception of the first few hours, the game is largely about being cautious and intelligent.
Dark Souls is a lot like Wind Waker's dark doppleganger; it's a great game which really should be played with a walkthrough at hand. You can probably beat everything yourself...but eventually your patience will dry out.
And as to anyone who says Dark Souls' controls are clunky...please remove the controller from your rear end. The controls are some of the most immersive and accurate I've played. It's a lot like Parasite Eve 2. The only problem I have is that it was designed for the PS3. The 360's D-Pad is one solid button with four inputs under it. There have been many times I wanted to circle through my inventory only to change weapons as well.
