In any other line, this game would be an A+. Following Sands of Time, though, proves too much.
Numerous features in this game were improved upon from its predecessor. The combat is more involved and makes you feel like you're actually "doing" something; the path is non-linear and therefore you're never sure if you've covered everything; by the time you're 20% into the game, you haven't seen every enemy, as in SoT.
However, the romantic aspect is lost. The "romance" in question isn't the girly-love type, but the whimsical, fairy tale-like feel in the SoT. The environments are still impressive, but darker and therefore just depressing to look at, whereas I found myself wandering around in SoT just to look at stuff. The prince's humility is gone, as is the Middle Eastern soundtrack, replaced by anachronistic heavy metal. A small bit that is a huge loss, in my opinion, is the prince's "No, no, no, that's not how it happened" when you die, a great addition to SoT that made the whole thing feel more like a story than a game.
Warrior Within is a true action/adventure game. Most of the tougher points require brute force to get past, so don't expect to finesse your way through it. While you may not need every combat feature (I think I used the area attack once, just to see what it does), you will almost certainly need the slow-time technique which was extraneous in SoT. The fights are harder, though not impassable by any stretch of the imagination.
The puzzles are few. Instead of stopping, getting your bearings and having to solve some puzzle to advance, you will find you unconsciously solve most of the puzzles simply by following the logial path through an area. One puzzle toward the end comes out of nowhere: there is no reference to it earlier to tell you what the heck you're supposed to be doing, and you'll probably spend 15 minutes killing a dozen enemies before you realize it's not necessary to fight them to solve the puzzle.
Also, watch out for glitches. There are innumerbal game-ending glitches (saves don't load or load improperly, a platform fails to raise where it should) and non-fatal yet aggravating glitches (the prince's body literally disappears, enemies spawn endlessly when there should only be two or three).
Like many gamers, I guess, I fell in love with the prince (no homo) in Sands of Time and want to see what happens to him in the end. If that's you're approach, you're like me, wanting to get the "gameplay" out of the way to find out if this dude ever actually changes his fate. Then you watch the alternate ending and realize this didn't really bring closure to anything. Shoot.