This was such a large update to vBulletin that every template had to be reverted back in order to include the new functionality. Since this forum is highly customized, it has meant a lot of work reediting the templates. I'm going to list what stuff I know is missing still, and what I have restored. Once I am done with the template edits, I will announce the new features.
1) Custom smilies - the popup was missing from the quick reply window - it should be there now.
2) Forum filter - it is back in Edit Options in User CP
3) Moods - apparently, a new version of the Mood plugin has been released, but there is some complexity in upgrading it. The current one is still showing on the blue skin, but the selected mood doesn't show anywhere. I will update it as soon as I figure out how to protect all the existing custom moods.
4) Tags - vBulletin integrated tags into the new version, and as some of you discovered, by default anyone can edit them. This is a REALLY BAD IDEA so I turned off that option. I actually prefer the older tag plugin and will probably go back to using it - I converted all the old tags to the new format.
5) Special fields on the posts - the fields showing
SL Business name, SLShopper ads, arcade top scores, awards, etc... have to be restored still.
6) The Dark
SLU skin needs a lot of work still - the reason for the switch is the company that made the previous one seems MIA and does not have a skin compatible with version 3.7. While it is under editing, it is not the default but will be switched back to the default soon.
7) I am not sure what effect this had on the mobile skin.
If I think of anything else, I will update this to keep you posted.