The only Prince of Persia game I have ever played (beside the classic side scrollers in the early '90s). From what I understand there is a trilogy of PoP games and Forgotten Sands is what one should call an interquel, an episode that portrays the events in between those that were explained in two other PoP games.
The story follows the prince who tries to help his brother, Malik. Malik was a bad boy and unleashed an army of sand creatures so it is now up to the prince to save the world from Solomon's Army. Story-wise, it offers nothing special, but I liked the struggle between the two brothers - there is a certain tension there that makes you want to proceed and find out how it'll end.
When this game came out, Ubisoft was in deep development of the 2nd or 3rd Assassins Creed game. You can only imagine how fluid the climbing in this game, right? Some of these climbing sequences are actually a bit over the top - the prince can later on solidify water to use them as columns or can rebuild the environment if it's in ruins (only for a short period of time, though). Some powers can be used against the enemies, as well, and while fighting you gain experience points and eventually, you level up. This is just a minor RPG component here as PoP is essentially an action-adventure game far from true RPGs.
Forgotten Sands has a very high production value that all Ubisoft games can be associated with. It's a relatively long adventure that all gamers should participate in. If you have never heard of the Prince of Persia franchise, you might pick this one up for starters.