I did an upgrade to Pro myself and had only one application issue, my antivirus didn't want to comply. I would assume that the issue your friend had with VS 11 for win7 not working is due to the difference in functionality between win7 and win8, and the winRT APIs becoming available.
Just me, and I'm a self proclaimed ubernerd, but I would go for it. Do a fresh install of VS2012 as well just to limit any weirdness. Everything else has worked wonderfully, I even regained some video card functionality having lost it during an update to win7. Been coding more than ever since the upgrade too.