I actually just finished this game last night, and I loved it. Parts of it is very puzzle oriented, but jumping and running across walls is alot of fun. I enjoyed figuring out "Oh, so you jump THERE and do THAT!" In that respect, it's a bit like the old good Tomb Raiders, but, without so much swearing at the game and frustration, since the control isn't as sluggish, and you can rewind time if you just jumped wrong.
The combat is alot of fun, though anticlimactic at the end of the game. The last sword is a bit cathartic, but ruins combat from then on.
I would have liked to see a few more secrets in the game, of finding a hidden ledge, and there is something to unlock, even if it was an art gallery or something like that.
I also liked the banter between the two of them, it helped move the game along, considering it was mostly puzzles, and not a lot of plot movement for most of the game.
I can see how this game may not appeal to you if you don't like that kind of game, but if you like that genre, this is an excellent game. I'm looking forward to another game made in this style. Hell, there are alot of 3rd person games that I wish I had such freedom of movement and control of as the Prince.
And as to replayability, I DO plan to play it again (hell, I ripped through it in 5 days). I just have to finish Beyond Good and Evil and Splinter Cell first.