I didn't want to insult anyone, sorry, but just thought that the Win version looks 'cheap' w/ its huge areas of blank space and the whole spartan interface. The Mac version looks much nicer, but that's probably partly due to the OS. Maybe it looks better when it's filled with lots of tasks.
Fonts look fuzzy, a little (in the program interface) resp. very (in the help file). Never noticed this fuzziness in another program.
I'm running XP SP2 w/ ClearType enabled (but I tamed it a little w/ MS ClearType Tuner).
There is also a problem w/ German 'umlauts' (ä,ö,ü,ß): When I enter a word containing an 'umlaut', that letter is surrounded by additional whitespaces on save (I tried to attach a screenshot here, but got an error back, saying that the upload directory was not writeable).
Edit: Now I uploaded the screenshot elsewhere and embedded it here. Note that I did not enter those spaces.
Edit (2): This problem only exists w/ the Windows version, it doesn't happen w/ the Mac version.