They're extremely picky about everything you do or say.
They need constant attention to keep them going.
They crash right when you need them the most.
The good ones are way too dependent on their network.
They have problems running independently.
They store things using in a FAT file system.
They go nuts every so often for no apparent reason.
You can rent one for a while if you know where to go.
They are only good for a year or two before you need to replace them with a faster model.