I apologize in advance that this is not a short answer. But that is because whether or not it's hard is not something that you can just answer in a few words. The difficulty in TW2 isn't the same kind of difficulty in the Ninja Gaiden and Shinobi games. Those were difficult due to needing fast reaction speed and timing. TW2 is difficult because you don't get spoon-fed anything.

The difficulty in TW2's combat that you have heard so much about came from three main things:

1.) When the game was first released on PC there were issues with pressing keys on the keyboard and Geralt wouldn't respond. Those issues have been fixed, at least for the PC version, so I would assume the 360 version doesn't have this problem either.

2.) I was so used to games where the first level is basically a very well designed tutorial that holds your hand and teaches you how to use everything. This game didn't have that when it was first released. You had all your magic right at the start of the game. And because you have all your magic right from the beginning, the game expects you to use those spells. It expects you to use all of them and to use the right spell for the right situation with minimal instruction on what each one does.

So as long as you keep that in mind and look up what each spell does in your in-game Journal, it shouldn't be too frustrating at all. Plus, the developers have added an optional tutorial stage that walks you through everything. So if you do that first you should be set. But I will give you one tip, a spell called Quen is a shield spell that protects you from damned near everything, but disappears after it absorbs a certain amount of damage. In the beginning, it was my very best friend, especially since you can't really block enemies, only dodge-roll away from them.

3.) This last part only applied to me because I had played and beaten the first Witcher game before playing TW2. The sword play, method of avoiding damage, and a couple of the magic spells I mentioned above are very different in from the way they were in the first game. So here I was using spells, thinking I knew what they did, and then realizing that things had been changed on me. Or trying to avoid attacks only find out that Geralt doesn't really leap around like he did in the first game. But like I said, there is a tutorial level now, so if you do the whole tutorial you should be set in knowing what everything does.

And once you make it past the first level and you start having to deal with monsters, it is the player's responsibility to find someone in town who sells books about monsters, buy and read the books, learn their weaknesses and the best strategies for fighting each monster, and then preparing for them each time you head out into the wilderness(by preparing and drinking the right potions, making the right bombs and traps, having the right spells ready, etc)

Sorry if that was a bit long. Hard isn't bad at all if you do the necessary prep work and actually learn what abilites you have. Just make sure you actually select "Hard" and not "Insane" or "Dark" difficulty. If you die in Insane mode your save is permanently deleted and Dark mode is a whole other beast.