If this reviewer is accurate in his assessment of the performance of his batts, it seems clear that the quality of these batteries is entirely inconsistent. All the cheap after-market batteries I have bought for cameras, mp3s and other gizmos have been substantially below the performance of the originals supplied with the item.
Usually, they are so bad that they fail very quickly - commonly, refusing to take a charge - and I zap in a complaint p.d.q. and get my money back. So far, this ploy has worked. I'm hoping that one day I get a battery where, like the one in this review, they accidently put as much 'juice' in it as one of the originals!
But, by and large, these 3rd party batteries are indeed a false economy, as others have said. The exception I would make to this rule is that 3rd party batteries from the top-end photo retailers in the US - 47th St, Adorama etc - can be trusted because US consumers tend to be particularly unforgiving of being sold crud.