One year ago, my girlfriend was using Evernote (on my suggestion) to write her travel journal on our trip to Southeast Asia. I saw her note sync a bunch of times (the iOS app shows a little blue arrow when it's uploading). But one day she opened it and the note was gone. I contacted support but they couldn't do anything. (They offered her a year of free Premium service and "apologized for the inconvenience".)
Since then, I've stopped recommending it to people because I don't want to feel personally responsible if they lose notes too. I also have a tinge of doubt every time I record important information. My biggest worry is Evernote quietly losing a note, because once I record something in Evernote I typically push it from my internal memory.
On top of that, their iOS app is incredibly slow. When I want to quickly jot an idea down, it's very inconvenient.
I've started using SimpleNote lately, which is far faster, but I don't know to what extent I should trust it to keep my data safely.