until the last week it would barely work at all. and that was if i could get it to load the store home! when it did load, i'd choose to install an app, wait five minutes, then it would give one of the various 'could not be downloaded due to an error' pop-ups. often, ever since they added Google Wallet integration, many of my previously purchased apps made me buy them a second time, and then there was the compatibility filter that got it wrong 90% of the time.
those issues almost always came up when my Google Account would show 'sync error' under settings, and forcing a manual sync, waiting half an hour, i might get ONE app to download, install, and process repeat.
To be honest, i prefer the Amazon App Store. i like the darker UI, the free app of the day, and so on. it has never errored out. i also prefer buying music through Amazon MP3 over Play Music's streaming that seems intent on eating my data plan, and prefer Kindle books over Play Books (again, UI preference). anything else i use Samsung's own versions, such as their email client, contacts and so on.
Back during the old Android Market, it worked perfectly fine for me, then Google Play took over, and ruined most of the AOSP apps by making their own and somehow shutting down the AOSP development (left a bad taste in my mouth), started flattening everything out, and worse yet, their new apps never worked properly. just surprised that it seems to be working well for once. i still don't like the UI or that new aesthetic that they're pushing on Android, too minimalist and basic, too flat, but when i must fire it up for something, at least it seems reliable.