I enjoyed using CouchDB, but ultimately found that MongoDB better met my needs.
The post is actually a great CouchApp tutorial, but I cannot stop wondering what was it. Being written back in April, before either CouchDB or MongoDB supported sharding, makes me think the reason was in the feature sets (can it be the MongoDB queries vs CouchDB MapReduce?) or speed.
Speaking of CouchApp, there is also this other extensive
Evently tutorial: ☞ Do it yourself.
Original title and link: CouchDB: A CouchApp Tutorial (NoSQL databases © myNoSQL)