Seriously, vertical terrain adds so much depth to combat in literally every genre possible that any camera issues are more than made up with an increase in tactical options.
This. Tree on a screen means - lost focus. Game means - its not about gameplay, its about camera movement. Any change from gameplay to camera stuff could not overweight bonus of verticality. If its not possible to add verticality without loosing gameplay focus then do not add such a thing.
Let's not get afraid of a third dimension because of some poorly placed trees. Or just make them see through. Not like a tree couldn't get in the way in a perfectly flat map either. The up-down motion of the camera is far greater issue that's actual unique to a vertical-focused area.
Moreover, you're going to have to position the camera at least a little in a large enough arena. The camera control in D:OS was plenty seamless to me. Middle-click and pivot, easy enough. Sometimes there are even objects in the way and I had to move around them. So long as that isn't constantly happening, that's fine. If it is, that's bad level design, not an unsalvalgeable concept that verticality might possibility be integrated into a top-down, turn-based game.
