The largest of them by far, the Paris Velib scheme has been a failure in numerous ways, with much suppression or playing down of the unpalatable truths.
I'm not equipped to comment on whether the Parisian scheme is a success or failure but I spent a few days in Paris at the turn of the year and saw quite a lot of rental bikes in use. To ride around central Paris on those machines takes a lot of bottle in my view but plenty of French seem to have the necessary courage from what I saw. Shame some of that spirit wasn't evident in 1940!
A couple of years ago, I spent some time in Lyon, (really worth seeing if you've never been) and the bike-hire scheme there, from what I was told by students, was hugely popular and I certainly saw plenty of the bikes in use during my stay. The local authority there had several trucks on the go, constantly balancing the supply/demand situation around the city so that there were always bikes available where required. On the face of it, the system worked well in practice.
Lyon has an interesting public transport mix, in that one can ride on a bus, a trolleybus, tramcar, underground metro and a funicular railway all in the same city. It's one of the places I've promised myself I'll return to if only for the fabulous restaurant food in the old quarter.
I really hope all these schemes prove successful in the longer term as I'm sure it will impact for the good by bringing about measurable car use reduction in our cities.
Indalo