I played a bit, but there are 2 things that annoys me: the footprint is really huge, for iOS, Realm.dll has 103 MB, so it means my app will instantly have 100MB more!!!.
The second thing(even more important for me) is about the fact that all my storable objects have to be derived from RealmObject, so no POCO support. This is pretty important because I will need to carry Realm dependency everywhere I pass my objects.