This is an awesome module. Marc has put in a ton of effort to make EV _work_, including finding, reporting and working around serious bugs in the linux kernel.
What really impresses me is how lightweight and fast it is, combined with an easy and elegant interface. If you're dealing with a lot of sockets, files, children, and/or timers asynchronously, EV most likely won't let you down.
I've used it in several projects and it's never acted weird or gotten in the way.