Biggest issue with it is that for not much more you can get an actual strain gauge based power meter. For only $60 you can get a 105 crank arm version of the 4iii Precision Power Meter (with DCR Clever Training discount) for example. If it was $50 or $100 cheaper I think it'd be a killer product.

Otherwise, worrying about accuracy of power meters is only something to do if you have 5 of them on your bike like DCR does. If you only have 1, why worry?