Not really. The big problems that are driving developers away are policy problems (mandatory sandboxing that's inadequate for the kinds of apps people want to

Not really. The big problems that are driving developers away are policy problems (mandatory sandboxing that's inadequate for the kinds of apps people want to write on OSX, lack of upgrade pricing, long delays in app/update approval, etc.), but, as a user, I've been seeing issues with the app itself for a long time. Things are particularly shaky around app updates: stuff like clicking an update button and nothing happens, or clicking an update button and nothing appears to happen but the update starts downloading anyways and a progress bar doesn't show until several minutes into a download, or Xcode updates that take (quite literally) several hours to install (after downloading) if you're not running on an SSD. These are things that got ironed out years ago on iOS, but I've not seen major improvements to the Mac App Store app since it was released nearly five years ago. If anything, it's gotten worse with subsequent releases of OSX.