Yeah, I saw the reviews too. Most of the complaints were actually about the battery life of the iPhone; which is no fault of this particular products (and they do sell an external battery pack.) Some complaints about the heart rate monitor. Which this particular kit doesn't include (and HRM's are notorious for drawing bad reviews from people who don't read the instructions and realize that they often don't work 'dry'). One or two folks broke it and one or two folks had issues with ANT+ sensors pairing.

About 50% would require 34 of the 68 reviewers to suggest that it didn't work.

Also; looking through the reviews; it seems most of the complaints had nothing to do with the product at all. One person gave it one stars and his complaints were poor battery life and that some of the big cycling apps don't work for the older iPhones anymore. And a couple complaints about the speed/cadence sensor not working with a couple of comfort bikes / townies / other types of bikes. If you break down the reviews where folks said it didn't WORK; there's actually only a couple.