I’ve been using Firefox 3 since Beta 1. After 5 betas, it is now at RC 2 3, which is going to be the version that “ships” sometime this month on Tuesday, June 17th. (Mozilla hopes to set a world record for the most downloads ever in a 24 hour period.)
There’s no point in waiting to update to version 3, except perhaps for add-on support. About half of my add-ons aren’t working yet. But the improved functionality of Firefox 3 makes the temporary loss of a few add-ons worth it.