I didnt rate Samui at all Bear. Was on Samui a few weeks ago (Bophut beach) found it a bit average. There is nothing wrong with it just felt there are much nicer places in Thailand.
I've been a few times now and always had a good time, I normally stay in the Centara area where all the bars etc are. It can be a bit overly busy with families but normally a good holiday after the peak holiday season.
I was in Phuket (Patong 8() and once out of that area the place was gorgeous - main street, beach are filthy so many horrible little bars and just feels dirty. We were in a pretty nice hotel and just taxied about the place, Old Phuket town is a gorgeous place but really quiet (would like to go back for a few days). Main street you just get stopped every few minutes, tuk tuk, massage, suits, sex, cocaine, hash etc.
OTC benzos though :D