Not surprisingly, there are tradeoffs. Here’s the CliffNotes version. Opera Mobile 9.7 and Skyfire do substantial processing of the web page on the server (as opposed to on the Windows Mobile client) and then send a highly compressed version of the web page to the client (less bandwidth). The result is they’re faster than Opera Mobile 9.5. Between them, Opera Mobile 9.7 if faster, and also does a better job than Skyfire of rendering the page. However, Skyfire supports flash, Opera Mobile 9.7 doesn’t.
I learned a lot from the video, as well as had a few laughs. You may too!