Have installed FF 3-beta (Gecko/2008021416 Firefox/3.0b3), what can I say? Looks promising, they have revised many gui stuffs, now it looks quite nicer. And yes, as they had been promising, now it works with Cairo and renders native gtk widgets. That's cool.
But unfortunately, just as it was with FF 0.9 -> 1.0, FF 1.0 -> 1.5, FF 1.5 -> 2.0, all my plugins screwed up. No firebug, not firefox-webdevelop, etc. 8(
By itself FF 3, looks quite stable, had no problems so far, no crashes etc.
That's it. Will waiting.