I kind of agree. When I first jumped into CK2 I was pretty overwhelmed by how much info was nested in the UI.
Thirded. All it really means though is that the player has sit down and work out what a few bits mean - do you expect the players to do that? If so then it's fine, otherwise you need it to be a bit clearer.
I didn't even realize how much craziness there is to the CK2 UI until I hopped onto a Skype call with a few friends and tried to get a multiplayer game going with people who'd never touched a grand strategy game before. After 30 minutes of character customization, we loaded in, and I spent about 15 minutes explaining the various screens, setting ambitions, marrying, assigning titles and councillors (and then deploying those councillors), the various mapmodes, how to enter the diplomacy screen, what the *point* of the diplomacy screen is... we finally unpaused and they were all quickly overwhelmed anyway. I've sunk thousands of hours into Paradox games so I totally forgot what it must be like to navigate half a dozen separate menus seemingly arranged without rhyme or reason, with walls of text everywhere and flavor mixed in with game mechanics making it hard to figure out what really matters. When you aren't experienced enough to filter out all the useless information, it's kind of impossible to not get lost.
I don't think there's a problem with the way That Which Sleeps' interface looks, but it's definitely less casual than Civ 5 et al... assuming the game even exists and isn't just a bunch of carefully photoshopped screenshots with some occasional video editing magic.