For some reason, people seem to think it's a key-value store, or some persistent database, but that's totally not it at all.
From what I understand, it is actually a key-value store and is basically a superset of memcached. Therefore, if my understanding is true you could use it merely as a key-value store as well and use its other features (native sets, lists, etc, pub-sub, and persistance) as needed.