The big benefit at the community Extras are the QA process. And I can install the applications directly on the device. No need to visit a mostly not working website.

I can't see anything like the Extras QT process at the official and Nokia own ovi store. They are not only selling expensive and not supported MMS messages to the N900 users (at a time nobody has ever seen a announcement of fMMS), they have not optified, not well tested applications in the store and the support does not work.

At example Cube Touch from Offscreen. Aviable since last year with a Bug in the application that it makes impossible to resolve this puzzle. And additionally the Application crashes very often.
Many times reported, per Mail, here at talk and in the comments at the store... but it is not fixed, no official statement, no update and the application is still in the store. Nobody has considered to remove it I guess.

The complete QA prozess is hidden or simply not existing. At maemo Extras we have a working QA process, I can search for problems in the past, who has voted for the package. Who is the programmer, what dependencies are there. Are there still not fixed reports at the Bug Tracker.

I don't have this at OVI. And there are many reasons in the past to don't trust applications from ovi!