I tested CouchDB 0.8 recently on Ubuntu Jaunty. I was very much impressed by its read performance and how it used javascript.

However I found that insert latency was very poor, and it could only about 16 inserts/second. My apps are generally write heavy (bulk not an option) so I felt it wouldn't be the right fit for me.

I also managed to accidentally cause CouchDB to use all my memory a few times. The fact that this was even possible out of the box would make me hesitant to use it in production.