Our team has been using GetJar for the last few months to host our Java based mobile app called Nokia Communties. It is claimed to be the 2nd largest app store after Apple's AppStore and it does an above average job of reaching potential downloaders. However, it has quite a few rough edges and there is definitely scope for improving app stores.
The main things I liked about the service are:
1. It's quite straightforward to setup and host your app
2. Provides decent options to target your audience (primarily by geography and device)
3. Quite a bit of stats to breakdown by geography and device
4. Ability to create & run promotions
5. It allows app hosting which makes it easy to share it across desktop and mobile sites
However, I feel there are a bunch of things it needs to do better. Firstly, the stats seem quite inflated. In our case it shows 3 times the downloads compared with registrations on our database. Secondly, the stats provided don't provide reliable information on success/failures of installations. Finally, customer sales & support are running a thin staff and aren't equipped to address issues relating to impressions and conversions.

The reason we are continuing promotions are because it's quite affordable. They charge by CPD (Cost Per Download) which is quite unique. Also, it works for us because our app is free. If you want to charge for your app then it doesn't support it just yet.

I would still highly recommend it to developers as this is one of the few cross platform stores which makes your job easier as a developer.
   
© 2011 Abhinav Khushraj Suffusion theme by Sayontan Sinha