Probably the best browser available on Linux. It's feature rich, and has tons of extensions and plug-in support.
However, my experience is that it locks up ALL the time, at least a couple of times a day.
This has been made a little less frustrating with the newer updates which new save your session so it can be restored when you restart the browser after a crash, but it's still a pain in the butt.
To be fair, I had the same problem when I tried Opera, so it may be a problem with Java plug-ins and such rather than the base browser on its own.