The key pros and cons are:
- The PS3 is more expensive than entry level BD players
- The PS3 creates more fan noise than most standalone BD players. Personally I can't hear mine, but clearly others can
- If you read around, once a BD player is calibrated with it's monitor, I get the impression that there's virtually nothing in picture quality between almost any BD player available (at least when playing BDs)
- Clearly the PS3 is massively more functionally sound, ie. can play games, streams better than some units, has the option of being a PVR if you add a PlayTV module, comes with iPlayer as standard. In short it's a very good media centre source
- Sony are commited to releasing regular firmware updates for the PS3 and will continue to do so for years. That's certainly not going to be the case for a lot of discontinued BD players, meaning that you might have a scenario in a couple of years that an old BD player might not be able to play some new BD disks
- By default you'll be using the PS3 controller for video control. Yes you can buy aftermarket remotes or adapters for say a Logitech RC, but that clearly ups the cost. Personally I quite like using the PS3 controller, but that's just me
So it really is down to what you want.