Here comes an opinion from someone who hasn't used FCPX but knows people who have. (I've read a few reviews.) Also I didn't read though this thread yet because I'm tried and want to comment on FCPX since that is my new favorite pastime.
As a tool for professional editing. No, it is crap.
As a tool for AMVs, might be ok to pretty good. FCPX complaints mostly stem from a bunch of missing features that are only useful if you are outputting or digitizing from / to tape or need to create an EDL / OMF for an professional online edit or sound mixing. It's mostly built for digital distribution it seems. The interface is different enough there will be a learning curve if you are used to FCP 7, but from what I have read it may not be a brad Avatar Music Video editor.
But I'm not dropping 300 plus add on dollars on it any time soon. My poor little dual 2.0 Ghz G6 won't run it so what the point?

