These guys are being a little harsh, it does actually have the potential to increase fps slightly, and reduce latency, especially for data heavy/reliant games like MMOs, as well as torrenting whilst gaming without any of the traditional ping worsening, due to the way it works, and in effect being a mini linux pc on its own. However the effects are varying, and I'd only ever consider putting one in a super machine if there was nothing else really worth upgrading.
The thing isnt completely pointless, its just very expensive for the benefits it does have, a viewpoint which comes across in all the reviews you can find of it - can be beneficial, has some advantages, but has a high price tag to go with it.