I've been using Evernote for a couple of months now and I think it's an absolutely brilliant tool for keeping notes. Matt introduced me to it and I'm glad he did; he talks about how much he's loving it too.
Like Matt, previously I used Microsoft OneNote (which I introduced him to a while back, heh); At first I saw no reason to change, I just thought I'd give it a go for a while, take it out for a spin. I don't really know why I did, I was really happy with OneNote.
But Evernote has one killer feature that has made me a convert (even if it does have a much smaller feature set):
Evernote is everywhere!
And that's it hold over me, that's why I probably won't be going back to OneNote. Evernote is simply and truly everywhere - in the cloud, on my desktop, on my phone, on my laptop. Like the Mesh, Delicious, Flickr, Skype and Box.NET before it Evernote has found it's way on to my list of indispensable tools for living and working in the cloud.
Find my public Evernote notebook here: