Might seem unrelated, but are you looking to use the PS3 exclusively as a bluray player, or do you also want to use it as a game console?
Because if you want to use it as a game console as well, regardless of how good it is or isn't compared to other players, I would advise against using it as a movie player. The drive in the PS3 is unique in that it can read PS3 game discs. Playing games and movies will slowly kill the drive's laser, and eventually it will stop working. Exactly how long this will take is anyone's guess, but the important bit is that this would NOT be covered under the PS3's limited warranty. It would be considered normal wear and tear.
If you're planning on only using it as a video player, then I think most reports say the PS3 ranks up there with the cream of the crop. But you should also look at the amount of electricity the PS3 uses compared to other players. If there's another player that's roughly equal to the PS3, maybe a little more expensive, but uses quite a bit less energy, it might well be the cheaper long term solution.
Also, the quality of sound is largely a function of the TV or receiver you have connected to the bluray player. All movie discs will still be likely to have Dolby Digital 5.1 or Dolby TrueHD audio, and unless you're using the bluray player to knock that down to stereo, it really doesn't factor into the equation on the audio front.
Can someone help me out with the quality of the PS3 Slim's Blu-ray player? Is it better or worse than the stand-alone Blu-Ray players out there in regards to screen quality and sound.
Thanks!! turbo_dean

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic