There's a whole zoo of 3D styles. From the semi-realistic look complete with SSS-shaders for skin that more resembles videogame cutscenes than your average anime (kingsglaive movie[0]) over the plasticy half-way look that has realistic lighting on flat-colored materials and outlines (e.g. altered carbon or the blame movie[1]) to productions that more closely emulate the common manga/anime style, sometimes even mixing 2D and 3D the same scene[2]
Attack on Titan heavily uses CGI for action sequences and dynamic camera movement. It's a fairly common technique that often goes unnoticed, but it's done very frequently in this show due to the crazy ziplining.
I believe when people are talking about 3D anime they mostly refer to the characters being done in 3D or it dominating the show in some other way. Props, cars, indoor environments, mecha and so on have often been done in CG for quite some time now. Of course context matters, a mecha fan may care more whether they're CG or handdrawn. If anything AoT is a bad example here because it makes it obvious rather than going unnoticed.
https://www.youtube.com/watch?v=L2BynvwE3Do