There is a bad news as well as a good news.
Lets start with the bad news first.
Macworld has done a review of various Macbrowsers.The scores were as follows
Firefox : 4.5/5
Safari : 4/5
Opera : 3.5/5
Omniweb : 4/5
Camino : 3/5
The review was appaling to say they least.Tim Luoma has written an excellent review of the Macworld review.You can read it here
The good news is that the leading German technology news site Chip Online has written an article comparing the features of three different browsers and Opera emerged as the clear winner here.More details available at my.opera.com
It may seem that I am calling the Macworld article as appaling only because Opera looses out in the review.It is not true.If you read Tim’s article then it would become clear to you how biased the author was.
Channel Register also wrote an interesting article titled Opera tunes up to overtake Firefox.Check that out too.