i'm sure "limited warranty" yun. and anyway, warranty does not necessarily mean "replacement". most stores have a 5-day to one month "replacement warranty". beyond that, you'd have to leave the unit for evaluation and repair. replacement lang kung irreparable, di ba?
and yup, they do replace defective items... a friend of mine recently had his 1GB usb flash drive replaced at their market! market! branch when the initial unit would fail after getting filled beyond 500MB. as far as i know, the replacement is working fine.