While I'm currently a Mozilla Firefox user, I was a very satisfied user of Opera for some time, enjoying some of its superbly implemented innovations such as mouse gestures. The "downside" of Opera, and a large impediment to its adoption, was the browser-embedded banner ads if you didn't purchase a registration key (which few did, as relates back to a prior entry where I observed that the only widespread competitors to Microsoft on the Windows desktop are free-as-in-beer software. Opera costed a marginal amount of money, so like many other pieces of software in that situation it remained a fringe application despite its many competitive advantages).

Opera has apparently finally tossed in the towel in its quest to sell their application on its ample merit (check out the feature sheet - native SVG rendering, super fast and lightweight, highly standards compliant, integrated RSS - This is a top notch browser), and is now offering their superb browser for free, downloadable here. Presumably they're moving to more "modern" revenue techniques like pay support, and perhaps partner agreements.

Even if you don't make it your primary browser, you simply must give it a try on your favourite websites and evaluate it on merit. At the very least ensure that sites you develop work properly in Opera as well.

[Slashdot has a discussion regarding this. Additionally I should note that if Opera sees widespread adoption, which I highly doubt given the lack of competitive application "shopping" among the Windows userbase, it may prove my SVG is dead claim wrong]