I'm really liking SMP so far. I'm a macOS/iOS/iTunes convert to Linux. I listen to music almost entirely through smart playlists. One feature I miss from iTunes is the ability to use a playlist as a criteria in a smart playlist, i.e., IN PLAYLISTX or NOT IN PLAYLIST Y.
This feature gave me the ability to create some pretty amazing playlists without having to over stuff my grouping tags (the main criteria for my lists).
Re: Smart playlist sort order
I agree with @spoo333. Sorting and (or at least) manual ordering smart playlists would be very helpful.
As I've said in other posts, my music listening over the years has been almost entirely through the many smart playlists I've created in iTunes. Now that I'm on Linux, I'm recreating them in SMP. With as many smart playlists as I have, sorting is a huge benefit.
Hope this makes it into a build.