(First - Disclaimer-Thingy: I am talking about Opera 9.25, Internet Explorer 6 and a little 7 and some FireFox version from a few months ago. I don't know what has changed in FireFox since then and I am not so familiar with IE7. From IE6 I directly migrated to Opera and stayed there. So, now for the main feature. Please remain seated until we have arrived at our final parking position. Thank you for reading Draconis Syndicate Blogair.)
Opera is great.
Now, I don't want to start any bloodfeuds^Wflamewars, neither do I intend to partake in the Browser Wars Reloaded. But still, Opera is great - in my opinion, Opera features the best browsing experience out of box of all browsers I know. (Read: Dunno about Safari, Konqueror, ...)
To state the obvious: Tabbed browsing is great, useful and fun.
To state something less obvious: Of course, all browsers have tabs. But for firefox, when I close the browser, firefox instantly forgets what tabs I had opened. Curiously, this does not happen when I kill firefox or it dies b/c of whatever. When I then restart FF, it reopenes all the sites I had.
Opera does not just remember the opened tabs upon closing, dying, reincarnation, obliteration and other modes of non-workingness, it also remembers all opened windows with their respective tabs. Greatness.
The ability to save sessions (read: windows with their tabs are saved and restored upon request).
Furthermore, Opera is really easy to use with just the keyboard. As Jeff Atwood writes in his blog Coding Horror, you can (more or less) easily navigate the links on pages. You can navigate from tab to tab in a myriad of ways - with the scrollwheel (hold right button), with C-Tab, with the keys "1" and "2". "4" minimizes them. Joy.
I can't really compare that to other browsers except IE6, a little of IE7 in out-of-the-box condition and the occasional use of firefox. All of which didn't sport easy keyboard navigation (well, I didn't find it). And I can't tell, that the whole of firefox is easily used with keyboard only. IE6 certainly is not.
Well, I actually wanted to write a little more about how to use opera - but then again, their help page about it is very good. Greatness again. Besides, I gotta go ... ;)
Edit (three weeks later):
I found a few things that really trouble me with the Opera UI. To be fair, I want to share what I believe to be, hm, "suboptimal" about Opera.
For starters - I can close tabs with C-w, which is quite handy. I use it about always. Bummer ist, C-q, one key to the left, quits Opera without something like these "Are you really REALLY sure you want to quit?" message boxes. Luckily Operas session management remembers which tabs I had open. That's a real drawback. It's not helpful that C-e has some meaning, either. It's great that I can access about every feature with a key combinatione. Still, it's not nice that about every imaginable combination does something *g*