I have and do stream Netflix on my XBox, PS3 and Laptop. PS3 has the BEST picture quality of them all for some reason. Next is the laptop and then the XBox is last. The laptop and PS3 are using wireless. XBox is wired to my router. My kids use it way more than I do, but the quality of the stream is quite good on the PS3, in my opinion. Sometimes the quality on the XBox just sucks, almost unwatchable.
The XBox always has to re buffer. Sometimes get rebuffering on the laptop. PS3 seems to never need to rebuffer once the movie starts.
I guess it just depends on the device you are streaming with.