Our migration hasn't gone perfectly, either. But I'm staying out of it :D
It uses a lot of resources, though, I can tell you that.
I continue to find issues with XP and Outlook. Outlook 2007 can't share calendars now, MS knows about it. I really wish I'd just have went with 2010 but I was under pressure and figured if I was going to do it I might as well get up to date.
On a different note, has anyone tried Sharepoint 2013? I'm looking at deploying a new server at work, but am torn between Sharepoint 2010 and Sharepoint 2013 (after finding out what a pig's breakfast Exchange 2013 has turned out to be!)
I haven't. I've been thinking about trying it but I'm not sure we'd have much use. I really need to sit down and actually see what it offers.