Opera may be very good. I really don't know. I want a free browser and to use Opera as free, you have to put up with ads. And that is a no-no to me. I tried Opera a while back and it just didn't make my day. But I have heard that there are a lot of people that love it.
The more competition out there is good for us all. Each company has to keep working hard to make a better browser or else stagnation comes into the equation and sooner or later the downfall occurs (remember Netscape?).
And it seems that Microsoft has been doing the same thing with IE6. After defeating Netscape, there was really no competition for them and that breeds complacency and an outdated browser which needs a face lift, security fixes, and tabs (do you hear that Mr. Gates).
So, it is good that there are alternatives to IE now and that people feel so adamant about the one they are using. We sure don't want a world with just one browser that we all have to use whether we like it or not. :'(