I'm another happy streamer, especially since they started offering the service to PS3 users. Previously, I watched on a TV connected to a computer, but this is a lot better. I'm using wireless and only a 46" TV, which does result in some poor quality at times, but the convenience is great. I've also mainly used it to catch up on TV shows I missed (about to start Dexter). The lack of selection is a rights issue (mentioned above in the Warner post) as the studios don't want to cut into DVD catalog, VoD or hurt their newer content portals (Hulu etc).
Love my Roku box for Netflix streaming, and have bought some VOD (video on demand) movies from Amazon using the Roku as well.
Video quality is high, and I have not run into streaming issues with video interruption or pixelation.
The one downside I have found (and this is 3 movies out of dozens watched) is some movies say they are available for instant viewing but never stream- the download just hangs and never starts.
I'll be trying out Netflix on the Wii also when the Wii disk is available, and my next TV (Vizio? Samsung?) will almost certainly have internet capability as a decision factor in the purchase.