Already tried the developer preview version too, a long time ago, a little deception because of the fact Apple didn't keep the web applications function...
I think the biggest reason I'm so loyal to Safari and hardly use FF at all is due, not to features or anything that truly matters, but because I like the look of Safari. I don't feel at home using FF.
I am loving it. Very few problems for me. The incorporation of speed dialing like Opera and FF have , cover flow and some other little neat stuff makes it fun to use. The tabs at the top like Chrome has was a nice touch too. Well chrome and safari...