I love the new World Map. The revamped interface is kinda nice, but also pretty cluttered even with the ability to toggle bits on and off. Maybe a graphics options screen might be more compact since you could put the toggles there instead of having them on the main screen even when toggled off.
I knew that Item Sets were going away, but I was under the impression that they would be converted to just a static bonus you could pick from like the ones on the second page of bonuses. I liked the variety they provided to leveling, money making, or boosting stats (arena, race, etc) with out feeling like I'm having to save and spend.
The tower upgrade paths are pretty neat, but I wish Mega and Mega-Mega towers were explained more in the tech tree instead of making us do hours of research seeing how they combine in different ways.