I'm a big fan of the bikes too. Hellobike even lets you use your Alipay account to ride, so it's easy for foreigners who already have that set up. They appear pretty popular with the locals here too, many more people cycling than in previous years, to the point that the local government has been pushed into providing some basic bike paths. Some of the local press seem to have taken a negative attitude to them though, complaining of them clogging up the footpaths (while somehow ignoring all the empty parked cars that have been doing that for years).

I'll be interested to see if the bike companies keep them around when winter comes! In the past, they've withdrawn them around October/November.