Having used dockless Mobikes in Paris (despite being a fan of classic Velib', they managed to fuck it up so badly last year that it's close to useless now) I can attest to the convenience of bumping into a bike, using it for a short ride and just dropping it off wherever you are going. Velib was annoying in that it was sometimes hard to find a bike or a dock to leave it. Citymapper really was instrumental to using Velib' because it had a good UI to spot bikes and docks.

The Mobike system is global so it also works the same in other cities (one of the big Uber advantages: get a ride exactly the same way no matter where you are).

All in all I really like the concept. The Mobikes themselves, on the other hand, suck. They're way too small for a general western population. They're probably designed around the average asian height.