I'm giving 4 stars because overall the product is good, even though it's not perfect (but then again, nothing is!). Note that this is a review for the previous version of the Swytch. I have yet to try the new one, although I was satisfied enough with my experience that I ordered the conversion kit for the new Swytch. The battery is powerful (I have the pro version), lasts about 40km (if I did the calculation right based on my commute) and it's a great advantage to have the battery pack on the handlebar so that I keep the mount free for bags (I converted a Brompton). I haven't had any problems in terms of maneuverability with the battery on the handlebar. The addition of the swytch did not impact at all on the bike's folding mechanism, but has made my commute easier. I did wait quite a few months to get the equipment (somewhat expected, but it did take a long time). The other downside is that it could be easier to order spare parts. Overall, it's been net positive so far.