As a new convert to Mac (two weeks now, and, Man, it feels GREAT) there are lots of things to learn about how to use it, and to get the Microshyster out of my brain.
All in all the Apple and Mac side of everything works really well, and I have no issues with anything. Out of the box it just works, and really well (I can't compare with what went before such as Snow Leopard and so on) but Lion is working for me.
The problems come when I try to use Microsoft Office 2011 for Mac. It all looks good when you spark it up, but then it starts playing silly beggars. For example when I imported contacts from the old Outlook contacts, and added some birthdays to the contact cards. I expected to see them in the calendar, but not so lucky. So I added a 'reminder' which showed the birthdays in the calendar, but all a day early. I think the problem was a difference between the computer's time zone (I am Z+3 at the moment, and the default time zone in the appointment card). But even turning time zone off didn't help. So after several wasted hours I gave up on Outlook. ICal works well though.
The reason for trying to make Outlook work is that I have (ducks to avoid flack for being stupid) a Windows Phone 7... Live and learn: windows phone 6 was pretty good: the assumption that 7 would be better was just plain wrong. I don't think that wp7 works with Mac at all: I am not too bothered.
I hope to be able to contribute her at least a little bit, and thanks to all have left some ideas already!