Evernote is one of the handiest free apps I've ever come across. I don't use it a whole bunch as I usually use Siri to make quick notes about things in the native iOS Notes app while I'm on the go. But when I need to make a note or journal entry that I really want to hang on to, I like Evernote. (Maybe that's why they call it "ever"note.)
The new interface in Evernote 5.0 is real nice, I had a quick play with it on the iPad mini and it's a winner. Check it out if you haven't already.