There have already been some improvements, but combat at the endgame is way too slow. Buying your final upgrades after 0.5-1 hour, but combat progress (even with annoying popups) takes 6+ hours to catch up: not cool.
It would be nice if lower level monsters still contributed to terror in a meaningful way. Like 0.1% extra for each monster would make buying tons of the more basic kind still worthwhile.
This may be because you receive boosters in Catsanova leveling rewards.
CatsaNova Level Rewards of Sugar Boost
2 = 8 Sugar,3 = 13 Sugar,4 = 17 Sugar : Total = 38 Sugar
So if you nap, the next time you raise the kitties, you will not receive those 38 Sugar Boosts, you will only receive the boosts from leveling Kitties.
I hope those ascension credits or what they were called aren't going to matter a lot. It's quite nasty to ascend, and only then learn that you get points/credits based on your current amount of goblins, cash etc.
Otherwise still a pretty fun game though :)
Purchasing empty upgrades (archer/bomb tower) makes no sense. Not to mention that it's quite discouraging to save up for something expensive only to find out it does nothing and you have to save up more.
Others feel your pain, I added hp for those upgrades, however, adding something useful like a weapon included would be nice. I'll try to think of something :)
Every once in a while I check whether someone somewhere has the old version with the UI that looked pretty. Or maybe the UI has been redesigned again to make it somewhat appetizing again. So far no luck :(
 "Incremental Adventures"){kind=icon}
 "Square Man Idle"){kind=icon}
 "Little Idle Monsters"){kind=icon}
 "Defender Idle 2"){kind=icon}
 "Idle Hero Tower Defense"){kind=icon}
 "Kitty Catsanova"){kind=icon}
 "Idle Breakout"){kind=icon}
 "Realm Grinder"){kind=icon}
 "Press The Button"){kind=icon}
 "Grow Defense"){kind=icon}
 "Pixels Filling Squares 3.0"){kind=icon}
Do you have Dread stat artifact unlocked and leveled?