Yep, speed dial icons are too small. It's not that they've changed them, it's that these new builds can't be easily configured by the user. Why not allow the users to choose how the browser is set up?
Free in what sense? Neither costs you anything, but neither is open source.
Opera Mini does not include some features of full browsers and therefore doesn't work on all websites. Opera Browser for Android (the current name of Opera Mobile) is a full browser based on Chromium, and thus can handle any website that Chrome can.