I have around 5 sets for a number of different applications (kids' toys being the most prevalent) and they seem fine. They do appear to last longer than other batteries in my 550EX and 430EX, but that could be purchase justificdation syndrome.
Either way, they're not bad for the price.
TaKeN: whilst that does seem low, how does that compare to other batteries? And key question: did you return them?