Dave Smith about Riak:
Low, predictable latency data access and operational ease-of-use. When used appropriately (i.e. don’t expect Riak to be a RDBMS), Riak is able to provide an excellent latency profile, even in the case of multiple node failures. In addition, it’s easy to add/remove nodes while the system is running without a lot of operational juggling. Another useful benefit is that multiple nodes can take writes for the same key, thus making it easier to construct a geographically distributed data store.
Original title and link: The Main Benefits of Riak (NoSQL database©myNoSQL)