I'd like to know from the newcomers to the language, or even those who've been with it for the past few years. What's been the most complicated, frustrating even, concept (or part in general) of JavaScript that you've found?

I'm looking to write about them in order to help others who're just starting out, trying to get them to avoid the frustrations others experienced and get them to like the language sooner than later :)

Anyone up for a friendly discussion?