In my Samsung Galaxy SII Firefox Beta works great with one single caveat, links are unresponsive. It takes several taps to make them work, and in some cases, not even trying to tap on it several times does the trick leaving you stuck in the page. The taps that don't work mean that they do nothing, the link is not selected or the page is not zoomed. There's no UI representation of it.

Is there a specific page/set of links that you're having trouble with? Other people have reported this too but without a specific page to reproduce this it's hard to fix.