Got to admit i am a bit disappointed with this. I'm a massive Opera fan and was really looking forward to this, but its got a sort of flimsy feel to it. The rendering doesn't feel as solid as the webkit browsers.
It also doesn't seem to have that snappy, cached "back" functionality from Mini, where if you go back a page the last page renders instantly.
It feels a bit too much like Opera Mini, and where with Mini, it's forgivable because of the bandwidth savings, with Mobile it's less so.
As someone said above though, it is a beta.
As an alternative I found a fantastic browser the other day called "Charming" browser. It's part of the MIUI Rom (android re-skin) that some chinese blokes did. It's based on the android webkit browser, but the UI and tab handling are much, much better in my opinion. It also does have the "back" functionality where the last page is rendered instantly when you hit the back button.