What do you like best?
As opposed to RDBMS, documental databases (in particular, CouchDB) allow to quickly prototype and develop a fully-functional application. Being easily installed, configured and deployed, CouchDB keeps you from wasting time around tinkering settings, allowing you to focus on what's really important.
What do you dislike?
Despite being so easily deploy, I find that its Web Admin interface lacks some functionality. I get it - it's a documental database, and everything is treated that way, even its authentication & authorization scheme. But it's not *that* intuitive to setup users and roles, as one would expect coming from a RDBMS world.
Recommendations to others considering the product
Always get the latest version.
Always read the documentation. Sometimes, CouchDB introduces breaking changes in their API, and you'll have no idea why your app is failing if you haven't "read the Good Book".
What business problems are you solving with the product? What benefits have you realized?
I'm working on a real estate management and search platform. The main issue at hand was the diversity of data that a realtor can report about a household. There's a vast amount of features that aren't the same from realtor to realtor. So, the idea was to handle a baseline structure (the common denominator of house features) as well as support realtor-specific data, configurable from a dashboard. These specific features, however, must be used by the search engine as well. So, anyone looking for a new home can get to be extremely specific on terms of filters. For instance, if I want a house with two bedrooms, a bathroom, a fully-equipped kitchen, within 5 blocks of the nearest hospital and a supermarket 2 blocks away and with a garage big enough for a 4x4 vehicle, the search engine will harness both generic and specific data structures. CouchDB, with its flexible structure, allows to easily handle dynamic payload structures.