Jetpack is one of those plugins that clients only appreciate when it's not there (for example, a dreaded .com disconnect).

I used Jetpack on a client site to provide stats, related posts, and the twitter widget. Boy did we hear about it when somehow Jetpack lost its connection to .com.

I know lots of devs hate Jetpack, but I'm not one of them having seen directly clients reactions to the extra functionality, whether they realize it's from Jetpack or not.