The appearance and layout of the forums was dang near perfect before. I can't speak the the underlying code, but the new layout of posts is a step back, IMO. As has been mentioned, just too spaced out. I also want the choice of using the full screen width or not. Especially for subscribers, I don't so much space reserved for ads at the sides of the posts.
As to the "cleaner" look that's a matter of taste. I've recently updated the application I've written and maintained for my business in a similar, but not as extreme manner, i.e. almost no 3D look, square/straight lines and pleasantly contrasting color.
With Texags it's difficult to know how much of my opinion is simple resistance to change. However, it's also difficult to know how much was coded as change for change's sake. I hope they either dial back on the spacing and layout, or allow some user options to tweak the look.
I also don't like losing the ability to resize/enlarge the reply window. Mobile still allows that.