Have you ever participated in something on the scale of a world record? Well, I did! And though I didn't install Firefox 3 until two days ago, at least I downloaded my copy on the everybody-download-firefox-today day, June 17th.
I like it, it seems to run well, and I have installed it only on the laptop. Silverlight is still not compatible with it, so I can not watch streaming baseball games from MLB.TV on it, other than that, most of my most loved and oft-used extensions have been upgraded. The del.icio.us add-on is especially good. Give it a try!