I didn't watch anything all the way through, but I tried a number of movies. All of them say stereo on the profiles, but all of them played back in 5.1. The verdict: just like it is hit or miss for PQ on some of the streamed films (some look great, others not so much), the audio was quite good but it varied depending on the movie, but I would say it is easily at DVD level in terms of quality. I didn't watch something I am familiar with or could compare because most of my SD DVDs are in storage at the moment. On one movie, the bass seemed a bit light, but I can't say if it was due to the stream or if that is how it was mastered. I do have a few I think I can compare this week though.
The whole not having to use the disc anymore with the PS3 is a BIG plus
