I'm torn! 4 or 5? Good: Have had kit for a few weeks now (Go+) and it's great in my hilly area. Former tough rides are now easy. Still a workout if you want though. Also I found customer service responsive and helpful. Not so good: Delivery time. Did not meet what they said when I paid a premium for quicker delivery. They did deal with that premium satisfactorily though when they couldn't meet the time. **Still waiting for the quick release part for the battery Fitting was OK for a non-tech guy but 2 things: - make sure you've got a Torx wrench if you need to get a disc brake disc off. Alan wrench won't work. - fitting the PAS was hard. The directions didn't seem right ie the 4mm mentioned for pedal/frame distance and spacers appeared off. Maybe my frame is wider but I couldn't get enough space between the 2 contact points. Had to remove spacers entirely. Overall I'm happy now that it's on.