I have some EXCEL addins mainly for getting stock data in real time (or almost real time) from places like CBOE (chicgago board of options Exchange etc). Use a lot for Options trading etc.
When I try and install I get message : EXCEL IS NOT INSTALLED.
Major Showstopper for me this one although if you don't use addins it probably won't matter to you. Sounds just a small problem but this is actually a GO-NOGO type of situation -- it's NOGO.
(Same prob with on both Windows 7 X-64 and W8 RP x-64).
Quick roll back to Office 2010 before the Markets open on Monday !!!! -- always take backups when doing this type of testing -- fortunately I have the "Before" images.