First, there's no bookmarks menu. Yes, you read that right - you can save a few sites in a phone dialler thingy, but that's about it. To make matters worse, the download site lies about this and says you can use your bookmarks - then doesn't let you access them once you've "upgraded".
Second, you can't set up other programs to open files. You want to open ebooks with Calibre? Tough luck, all you can do is save the files. You want to open torrent files? Opera will do that for you - but it won't let you use uTorrent or another half-way decent torrent client, and Opera's built-in torrent client is not good. If you want to use an email client that isn't Opera's add-on program you're out of luck. It doesn't even seem to want to let me open PDFs directly, but that may be because my PC is set up to use Actobat to open PDFs, not Adobe Reader. I could go on, but you get the idea.
Third, there's no "open file" menu. You can save web pages but you can't re-open them, you have to navigate to them in Windows explorer, click on them, etc.
There are other problems, which seem to amount to a massive amount of dumbing down to make the program easy to use with tablet pc's and mobile phones. It's pretty, and appears to be fairly stable, but the problems are bad enough that I'm changing to Firefox as my default browser
Bottom line, I'd strongly recommend steering clear of this monstrosity unless you find sites that won't open with anything else.
later - forgot to say that there apparently were intermediate versions which weren't rolled out automatically to users. I think it's safe to assume that they knew the reaction in their existing user base would not be good!