I just (okay, a few days ago) released version 0.2.0 of btle.js to
npm. This has a bunch of API changes - the connect method now gives you a
Device object, instead of a Connection. All the ATT methods are now on the Device object, but, in addition, you can
access all the GATT functionality by querying the device for services, which returns Service objects, and services for
characteristics, which return Characteristics objects.

I'm also working on API docs for the whole thing.