Two main problems that I'm trying to overcome:
Exchange support. Evolution just doesn't cut it. It won't load my global address list and it doesn't seem to handle the "location" field for meeting invites. That means when I get an invite or try to send one I have no clue where our meeting will be.
CVS. I really like TortoiseCVS and can't find an equivalent that is as easy to use. I guess it's not a big deal, I could go back to using the cli, but what can I say, I am lazy. :)
Everything else has been good so far.