At this rate my MacbookPro 13″ (mid 2009) battery will not last the claimed lifetime of 5 years. About 2 months ago (end of august ’09) — as coconut battery correctly displays — I started out with a battery capacity of around 5450 mAh. This has been dropping steadily (99%, 98%, 96%) over the course of those two months, as far as my infrequent readouts can be trusted.
I have not seen many reports about bad quality. Though one discussion post also reports a quick drop to 96%.
At 29 cycles, I have run this battery down below 50%, and charged it back to 100% about once every two days, give or take. Going below 5% at least 5 times. My only hope is it took this long for the battery to get calibrated to its actual charge of 96%. Only time will tell.