That's because it is stupid easy. You don't even have to think to do anything. Nothing in this game is even remotely difficult, and it requires no brain power to play.
The controls bother me a lot, probably because I'm coming to this game right after having played Mirror's Edge. There are too many moves on just one button, and the game assumes too much as to what you're trying to do. There's also no momentum when you're running around, which again is really weird after playing Mirror's Edge since everything in that game is based on having enough momentum to keep moving.
The thing I hate the most is the combat, because most of the time I don't feel like I'm in control of the character at all. The game tells you when to block, and if you try to do something else, you're fucked. It tells you to press a button, and you have to do it or else you're fucked. The prince moves really awkwardly in battles, and half the time when you press a button to attack he takes a year and a half to swing the sword, by which time your enemy has already hit you. I wish they would just use a fighting system that has worked well in the past (like Sands of Time) and just used that instead of trying to come up with this new fighting system. I absolutely hate it, it's slow and clunky.
The plot makes the game really repetitive; here's a map with healing grounds! Great job, you've healed one land. Now go to the other TWENTY THREE of them, and fight a monster and collect light seeds. GOOD JOB, YOU WIN THE GAME. It's just about as repetitive as Assassins Creed. Actually it's probably even more repetitive, cause at least in Assassins Creed you get to wake up from your DNA memory dream every once in awhile and do something different.
That being said, I've always liked Prince of Persia games; Prince of Persia was the first game I played when I was five years old on our old mac computer. I've owned pretty much every Prince of Persia game since then and this is the first one that I really haven't like that much. I'm still playing it, and I plan on finishing it, since I spent the money on it.