I am sure this has been batted around a time or two, but I noticed a very sizable difference in both the quality of audio and video from my Blu-ray (PS3) versus that of my Sammy upscaler. I mean, to me, it is night and day, to my wife not so much.........., but then again, she tries to tell me HD vs. analog doesn't look any different to her either, so take that as you will.
I have never played the 360, so I have basis of comparison, however, I enjoy my PS3 for all of the reasons just previously listed. Plus, I have no way to run wire to my theater in the basement, so the wifi was a God send. I was floored when I heard that the Xbox folks have to pay for online gameplay. What does that cost, $20-$25/month? With a year of service, you could have almost bought a PS3 had you saved the money. Personally, I really only play online, so it is huge to me to not have to pay for that "privilege".