I'd like to add a request for MC properly handling additional movie artwork files exported by XBMC ("tbn" files, actor images, fanart, etc.). Having the data in MC would be great of course, at least the artwork files should be moved/renamed together with the movie file(s).
Here's some documentation on XBMC metadata. I also remember seeing a wiki page where the handling of additional artwork is documented, can't find it right now though.
I fully agree with this post.
MC is overall really lacking when it comes to managing movies and TV series. I think JRiver should acknowledge that XBMC is pretty much the de-facto standard on HTPC's. They should fully adopt the way XBMC reads/stores artwork and information for movies/series (this would be particularly useful for people that want to use both applications, or migrate to MC).
This would also have the added benefit that third party applications for "Movie Collections" would also work (they usually support importing/exporting XBMC NFO and Artwork but not MC)
What bothers me most about MC, is that artwork and information is very easily lost from series/movies. This is particularly true with the current poor support for .ISO files (where it doesn't even create sidecars, and artwork stored where you will never find it if you need it).