>>I downloaded it yesterday.
>>My 2 cents: better than IE8, slicker UI, worth the trouble
>
>I can say pretty much exactly the same for FF4 vs. 3.6.xx.
>
>Only limitation I've hit so far is there is no official LogMeIn plugin for FF4, but their beta works fine (in limited testing).

I use FF on everything except my development machine on which I have been using IE because it was there and I didn't want to install any more software than absolutely required. I'm looking forward to FF4 - but not a beta.