http://www.apache.org/dist/couchdb/notes/1.2.0/apache-couchd...
Highlights I like:
* Speed improvements (native JSON parser)
* Autocompaction (no need to create daemons to compact db periodically anymore).
* Snappy compression enabled by default (should reduce db sizes and perhaps provide some speed improvements)
* Added built-in changes feed filter _view. This basically means you can use your view to filter your changes feed.