I have so far logged 4 Yosemite issues with Apple
  1. The previously mentioned boot partition switching issue
  2. The Labelwriter driver issue
  3. Cursor disappearing in an app -- this is reliably repeatable
  4. An issue trying to synch my iPad and iPhone.
and 3 with third party developers.
  1. Dropbox desktop and Finder functions do not work in Yosemite -- a known issue
  2. Dropbox won't launch in Yosemite. Fails with a message that Dropbox is out of date and needs updating.
  3. Checkmate test routines crash on launch

Still that is not too bad for a beta product


"All you've got to do is own up to your ignorance
honestly, and you'll find people who are eager to
fill your head with information"
--Walt Disney