And vertical multi-column tabs! And good performance for 100+ tabs on single core CPU-s! And speed dial! And integrated email/RSS client! And trash can! And notes! And so many more.
You can get very very close to Opera features with Firefox extensions. For mouse gestures there’s an extensions called FireGestures. It’s actually more configurable than Opera’s. Speed dial is in Aurora, but it’s very basic right now.
The rest I didn’t use/care, but I can recall there being an extension for every one of those things.
Not saying Firefox is better than Opera necessarily, it's just that Firefox is quite powerful as well.
The problem is that by the time you reached the functionality of Opera with extensions, your browser is bloated and takes ages to load, and a large chunk of RAM.
I’d have agreed with you just a year ago, but not anymore. Firefox made TONS of performance improvements and Opera actually got significantly worse at memory consumption.
At the end of the day, Aurora (with several addons) is usually below or around 300MB with my normal daily use, whereas Opera Next can easily go beyond 1GB of virtual memory.
