my biggest complaints about CouchDB revolve around design documents. The documentation on which portion of a design document will trigger the indices to recalculate are awful. I had to figure it out by asking in IRC and then still doing trial/error.

Cloudant is doing some very interesting things relating to querying on a CoudhDB system. They created a query syntax so that you have an option besides map/reduce [1]. I watched their webinar on it and it seems pretty slick, but I have not yet played with it. Also, it is not part of CouchDB yet so there is no option to run tests against locally to verify syntax, response errors, etc, etc.

Cloudant is working to merge many of their changes from BigCouch back into the CouchDB project, so one day I expect CouchDB to have multiple query options [2].

[1] https://cloudant.com/blog/introducing-cloudant-query/#.VLCSc...

[2] https://cloudant.com/blog/update-from-nebraska-the-cloudant-...