Not the best, but it is still a great "2nd*" title in the Quadrilogy.
Honest opinion now, it isn't worth paying £40 asking price. I'd wait until it comes down in price before purchasing. Or better still, rent the game.
Now that is out of the way, let my review begin (without spoiling anything major if i can help it).
Once again, we play as the Prince. This time he is sent by his father to his brothers kingdom to be "trained" in commanding an army (something we see at the beginning of Warrior Within when Prince is commanding an army on the boat). Once he arrives, the kingdom is under attack (same as the beginning of both Sands of Time and Two Thrones) and he has to find his brother and warn him about the "sands" contained within his palace. It has the Prince of Persia feeling to it, acrobatics the works.
There are new, and challenging puzzles within this title. And Ubisoft are right, 50+ enemies on-screen at once does look and feel awesome. The new "environment" controls are interesting, especially freezing water and moving the environment to assist your progress.
The original Prince voice actor returns, with the humour as well. Not as good as before, but still gets chuckles.
There are negatives to this title as well, for example.
There are no water fountains to save at this time, the game saves at pre-decided points. You don't level-up your life by doing puzzles or from drinking water as the three games from before did, instead you level-up from experience points earned from defeating enemies, which can be used to increase and add element powers, life, time-slots, power of attacks and how long you can freeze water for. Life is restored by smashing pots and defeating enemies, same for the time-power as well.
The combat does feel limited compared to Warrior Within and Sands of Time. Basically, the combat does have some acrobatic movements involved, but not much. You can kick and use the sword and you can use "elements" to assist as well, but this could have been improved significantly. There are no "sand" powers, so no more Eye of the Storm or Ravashes of Time from previous games.
There is only 1 sword upgrade, you get this later in the game.
The game does feel a tad rushed, looking at how Warrior Within feels game-play wise to this, Forgotten Sands feels like a animation game, no blood or anything.
There is a challenge mode, with 2 maps (both of which are not available at the start). Both can earn you experience points, but for those who think that you can complete these to level-up quicker before playing the game can be wrong. If you die within the challenge or run out of time, you don't keep the experience points earned. You'll have to complete the challenges to keep the points/new skills.
All-in-all, it is worth renting or getting for £10. Both challenges can be done in a combined time of 10 minutes (no joke), the main game lasts up-to 15 hours, depending if you hunt the hidden stuff down.