To be honest I thought it was pretty good, although the only PoP game I have played is the 2008 one and so I am only slightly familiar with the plot of 'The Sands of Time'.
A couple of annoyances though:
Firstly they did the typical Hollywood thing of "Oh no!, We lost the precious artefact. Oh no! We have been captured yet again". I don't understand what is so interesting about having the protagonists get caught or lose the thing they need to protect half a dozen times in a movie, it makes them look like morons.
Secondly, although it isn't a huge deal I found it strange that they changed the name of the princess for some unknown reason (I haven't even played much of the trilogy and even I know she is called Ferah).
It did have a few other issues here and there, and I would have liked a little more 'parkour' especially involving the dagger (after all, most of the game revolves around that) but considering it was based upon a video game, I'd say they did a fairly decent job.