These types of DBs are popular lately, for example, btcwallet now uses boltdb, while Monero uses LMDB. They're all kind of similar: full ACID semantics w/ MVCC, data stored on disk in B+ trees, async read/update with scheduling and transitory state patches for reads, multiple namespaces, nested buckets, etc.

AFAIK, bitcore is moving towards adopting more DB agnostic architecture, so in the future you can plug and play whatever crazy DB type you want.