The PS3 and Panasonic are very similar overall in quality with the Panasonic (perhaps) having a bit of an edge in upconversion.
The Panasonic is easier to use overall. It's a straightforward BD player - no Internet streaming or other features which may confuse things. The remote works alright, but really shines when dumped in favor of a good universal remote. Updates are easy and fairly automatic. It is basically silent in use.
The PS3 is fast - very fast. It is really reliable (as is the Panasonic) and has consistently received firmware upgrades to allow it to remain one of the best BD players on the market. Yet, the remote sucks, many people are turned off by the case design, and it is not as easy/straightforward to use. It can also get to be fairly noisy. But, my 80GB model may be noisier than the newer models out. Yet, in an open room, it is worth noting that the fan is extremely audible during quiet passages in movies. Louder than my projector for sure.
For most of my install work, I go with the Panasonic due to ease of use and overall simplicity and quality.
For my home, and a couple of installs, I've used the PS3. In fact, I've had a PS3 since opening weekend and haven't had issues with it. Yet, I do look forward to getting something that is just a stand alone player at some point so the PS3 can simply be a gaming machine for our home. Yet, there are times when I wonder why I would even care about that.