I've occasionally tried Opera on the desktop and never been particularly impressed. But on my N900, this is everything MicroB SHOULD have been. Well thought-out controls that are unobtrusive and it renders lightning-fast. Even on my own Web applications which are very Javascript-heavy, pages that MicroB takes over 10 seconds to render are ready in Opera in only a couple of seconds.
The only minus point is that there's no immediately obvious way to search through long

Excellent for slow connexions, a true mobile browser. But still I prefer MicroB when the connexion is faster to get a real browser. Both are good in their ways :)