It's not that Moz Analytics is hard to understand once you have it set up. It's mostly that getting it set up is so difficult.
Moz Pro will let you set up your campaign for www.mysite.com, but Moz Analytics will not - it keeps switching it back to just mysite.com (stripping off the www part). Ask David Lee there at Moz, we've been working for weeks to get this fixed.
Also when you put in Competition URL's it does the same thing, but it should not. The stats for a www.competitor.com are often different than the stats for competitor.com - and we need to compare to the version that they show up in Google as.
The campaign set up screens really need a bunch of pop up tips on what sort of input is expected in the blanks. For example, we had a bunch of problems entering our G+ business account because we were cut-n-pasting in the URL that appears while we are logged into our G+ account - but the Campaign set up form wants the URL for those who are NOT signed in (which doesn't have /b/ in the middle). Nothing on the page tells you this.
I would start with doing a usability study on the Campaign Set Up screens before worrying about usability of the reporting screens. Use people who do not live and breathe the latest and greatest online interaction. If we get terribly frustrated just trying to set up a Campaign, then we will already be primed to look unfavorably on any little problem with the reporting interface.
Maybe I like Moz Pro better because the Campaign set-up steps are a little more old-school, a little easier to understand, and it's less likely to change what I enter...