Fairly limited without ReSharper, which makes it slow; language support is not particularly great; updates have made me lose half a day's producitvity (although that's par for the course for Windows); weird keybinds...
And of course: Windows-only, not open source and not free as in free beer either if you don't meet certain criteria.
Agreed, VS is the best IDE out there by far. Still a shame that developing in VS implies developing on Windows.