I understand exactly what I batman and Sisiutil say. They went through all the trouble to make the game 3D and didn't even incorporate the aspect into the gameplay; yet they kind of had no choice if they want to stay in the game. I love the graphics, they're really nice. But, it must be asked: What do they add, besides immersion?
More importantly though, I also get annoyed by how "cluttered" things get in the latter stages of the game. Some of my games become sheer pandemonium by the Industrial Age and beyond. However, I feel it's like that on purpose, to give you a sense of how complex, busy, populated, etc., more recent times are, as opposed to early civilization. The idea for the game is to get harder as you progress, and the new 3D graphics sometimes act as an unintentional extra hurdle.