It was supposed to be much more lightweight then network-manager. A light-weight alternative. Afaik however, I don't think network-manager is _that_ bloated to deserve an alternative. But who knows evolution will show which one will be better in the end. I just hope it's not a NIH syndrome thing.
Does ConnMan help you tweak other stuff based on which network you've just connected to?
I've scabbed stuff onto the back of both NetworkManager and basic dhcpcd, so it detects whether I'm at work, at home, some other network, or disconnected. It then tweaks any number of things, based on that information. But it's scabbed on, not terribly clean, and I wouldn't mind if some other package picked up the heavy lifting and did it better.
The only reason why i'd see this as an alternative is if it helped simplify the more advanced stuff .. like IP routing .. at the moment i cannot for the life of me share my Mobile Internet which has a dynamic IP address over a wireless network with NetworkManager .. the only way i can do this is to log into my windows side so i can wirelessly share the internet with my gaming console .. I've tried various solutions on the internet via commandline or using firestarter's "share internet connection" but none of that works .. so i'm keenly awaiting something simple .. i'll prob get a router in the future, but im pretty sure that would be a cool feature