So just out of plain old insane curiosity, I've been wondering if dmg's confuse folks. If everyone could weigh in on it that'd be great.

Here's what I'd really like to know

* Is it hard to describe to new users?
* Is it hard to teach new users to use them?
* Are they easy or hard to use?
* Are they harder to use than say.. a zip file?
* What about internet enabled dmgs? If you know what those are, what do you think?