Riak quick list of things that are amazing to me:
- No single points of failure
- Every node in the system is structurally equivalent (lots of cheep hardware)
- Nodes can be added at any time
- Scales to large cluster or small (developer box)
Right now the map reduce is only in Erlang and I think that is the biggest issue. I don't really want to learn erlang to do map reduce however it is better than SQL over relations. Building a real application with CouchDB made me find out some real issues it had. So that is my next step.