I've never had an orgasm from it, but I enjoy it very much... I think the key is good preparation. Since I like it even more than my fiance, he never urged me to do it, I think that helped a lot.
We actually already did it the first time we had sex, which was when I lost my virginity, and I couldn't believe how good it felt.. I had always assumed it only was nice for guys, because of their prostate.. but anyhow lol
Most guys probably aren't into it that much, but I think a rim job is the best preparation.. if not that, use your fingers. And make sure you're extra horny, I can only enjoy it after we've been doing the regular way for a little bit.
oh and word of advice. Do not go back and forth between the two. Bad bad bad!