I just upgraded to 18 from 17 and there are 2 things I didn't like,
1. The cost, 29.95 to upgrade from one version is a bit much. I get an error message when I start mc18 after upgrading. Something about the wrong account and then media server and mc18 in the start up? I used the same email and account I've always used. I've also been using Media Center since Version 12.
2. The inability to properly recognize my Nano Generation 7. It will let me play, edit (as in change the tag info) and delete the songs, but not sync or add new music. It's also not listed as a recognized device. I know APPLE broke it, but I was unaware of your refusal to support any new versions of the IPOD until after I purchased the upgrade. I HATE ITUNES, GARBAGE SOFTWARE.
Since I just upgraded last night, I haven't looked at all the changes. I hope it is worth the price.