Spent a few hours mocking an Android screen with this tonight. I have to say it's streets ahead of Balsamiq. Like such as:
* Import images by URL or from IconFinder website
* Completely up-to-date Android components
* Properties and tools always present, by nice use of expanding/collapsing
Balsamiq's pretty good for the stock stuff it provides, but that's somewhat minimal and very skewed to early iOS. Once you have to go online to find community stencils, there's not much out there and importing it is buggy (ie often images are missing). It seems to be on life support unfortunately, so I'm glad to have discovered this.
Also, a little big detail I like is if you select multiple elements, it puts a single box around them all instead of keeping them selected individual.