They suffer from an odd-size complex.
At a 1/2 L, they can't quite fit into a pint glass nor take up two 12 oz. They only can fit 4 to your normal 12oz 6 pack.
They do have a sense of being so awesome when you can fill(thanks BMBF!) a few up right before heading to the beach and not having to sanitize caps or keep a capper when you only keg.
Plus, that sound when you flip the top and make a popping sound is so awesome, it makes your brew taste better*.
*not really, but it still sounds cool.