We had a few issues after upgrading..... No errors or warnings during the uppgrade were seen, there were no problems retreving archived items and so on, but you could not searh the archive.
Thanks to a post by Micah in this forum the problem were quickly solved though. There were some stored procedures that had changed ownership from dbo to the Enterprise Vault service account. After changing that it worked.
Also I have a very irritating 40966 event about monitoring that I cannot seem to get rid of, but I'm working on it now. All information about it I can find points to early versions of EV 5, not EV 7.
Good luck
Micke