I am the proud owner of a galaxy s2 and very nice it is too.
The one problem (so far) I have is that the audio/lip-sync is off during video playback.
I can see this seems to have been an occasional issue with the original and that a factory reset might fix it. I have tried this on my s2 and it hasn't fixed it.
Can anyone else reproduce this? It occurs on flash (iplayer etc) and mkv's from the sd-card..