haha, why don't you post some screenshots and introduce a bit more detail. Too vague isn't very helpful..
Indeed.
First, it's automatic for tab remembrance. If you close out or it crashes, you can reopen the exact same session of tabs you had, or you can save a particular session, maybe your Macrumors session, which has a bunch of threads you're watching..Don't want to go through and find them? Save the session. Then the other options, of course.
Those options are of course also able to be set default.
What makes it even better is, Opera has had these options for a long time.
Customisation is easy as well. Need a new skin? Simple:
Want some widgets for your web browser? Plenty of great stuff:
I know Opera has had Widgets for much longer (I don't remember if Firefox has them at all ?), but customisation, maybe not.
Of course, there's also plenty of good productivity features. For example, have a couple of pages to look at? Need to copy from one page to another? Love OS X's Exposé? Well, Opera has a feature that is kind of like Exposé for your browser. It spreads them out alongside each other within the browser for easy viewing. It's also easy to reverse, and go back to normal.
Panels are also easy to show/hide, for easy access to Widgets, built-in notes and comments, history, et cetera, and you can even add panels if you'd like, quite easily.
Here's the generic panel:
And it looks good. The browser's not amazing looking, but it's decent.
And of course, my favourite feature is that you can search any search engine from the address bar. And you can add search engines and such of your own. Want to search google? Instead of typing google.com and then clicking and searching, or navigating to a separate search bar (there is one, though, if you prefer), just type g hello, with hello being the thing you're searching for. Or if you want yahoo you can type y hello, or whatever else. Got one you want special? Let's say...supersweetjobfinder.com (I didn't look, is that a real website?

) is just a search engine for job positions...just add it to the list.
Also, I don't remember, does Firefox have the Wand tool? I know Opera's had it for a long time.