Range sharding (for saas,shard by client_id).
No sorting by value on couchbase indexes? And many other small features.
On the other hand i love about couchbase: no mongos,all servers equal.
I'm curious on the index sorting though, do you mean in terms of specifying what to sort on, or that you can't sort at all? As far as I understood the new indexing capabilities allow at the very least to sort on numeric values and similar.