I tried Opera 9 Technology Preview 2 (TP2) almost all day yesterday, and all I got was frustration from using it. It does have a smooth interface and the widgets seem to fit in quite well, but there are a lot of bugs that need to be fixed. The one bug that would keep me from using it as my primary browser has to do with GMail.
GMail has never been supported by Opera which would be why GMail complaints is such a popular topic in the Opera Forums. GMail may work the first time that you visit it, but each visit after that Opera TP2 will freeze up after displaying ‘Loading’. This is definitely reproducible and in my opinion is completely unacceptable. This is also an issue, though not as frequent, in their version 8.51 release of Opera. How could a web browser not make itself compliant with GMail, especially with the release of chatting capabilities soon to come in GMail!