I've got truly offline replication (as in you can run me on Android and your laptop and keep them synced via the cloud).

Also, none of the other NoSQLs are really set up for schemaless queries like I am. Incremental map-reduce lets you normalize a bunch of different heterogenous document structures in your view, which is more flexible than the key-path indexes Mongo has, and more real-time than Hadoop/Google style map reduce.