Unlike Opera Mobile, Opera Mini crunches pages on a server for viewing on your Java phone or BlackBerry. The beta has a snappier interface geared for touch or keypad control, and adds tabbed browsing, speed dial, and a password manager.
The idea is to mirror the desktop version as much as possible. Open a new tab and you'll see the visual speed dial thumbnails, which you can also customize based on your browsing history. The new version can also be set to store login details on your phone.
As with Opera 4.2, YouTube videos will play via your phone's native media player, and there's still no Flash support. What also sucks: This beta won't support Skins and Opera Link, though both should be reintroduced as development continues.