Well now that IBM seems to have given up on Notes and Domino I am moving into new adventures (while still doing stuff with Notes and Domino). I own a Macbook Pro but so far ran a Windows machine as my primary desktop. To become more productive I ordered a Mac Mini this week (yes I am aware it is a bad time buying a Mini because it will probably be refreshed soon).
This makes me a Lotus Notes Standard user on the Mac and I never expected my experience be that bad. The client is dog slow, the integrated Sametime client causes constant crashes (so I just disabled it and LiveText too) and the fonts look very ugly.
I am aware that Microsoft Office on the Mac has its issues too so maybe developing for the Mac platform isn't that easy.
But with my current experience I am not sure if a Notes Mac client is a good idea at all.
Off course this is just my rough experience with just 3 days on a Mac. I am happy if it works well for others.

On a positive note developing with TextMate and/or Netbeans on the Mac really is a pleasant experience.