ZAPT is a massive project, currently at 13,650 lines of code. The only project I know of that is larger: Return to Blockland... and CityRPG v3.
ZAPT is complex. There are 6 ScriptObject overlords, including the ZombieDirector SO that is 1,000 lines of code just by itself. There are several massive systems stuffed into the mod, ranging from Minigame events, to a neural network that keeps the HUD synchronized for all players to the best of my ability.
ZAPT is simple. Despite how dense the underlying code is, it's remarkably easy to set up and add on to. I downloaded Phydeoux's Zombie Dogs mod and, timing myself, was able to get the zombie dog into ZAPT in just under 5 minutes. Most of that time was spent trying to figure out what the hell the "ZombieDefault::" parent calls were for, and getting 7zip to work in the Program Files directory.
The gamemode itself takes much less time. I don't understand how people can complain about it. Put spawns, select zombie, play game.
ZAPT is pretty. Smokers emit smoke, boomers puke and explode with a sort of unrivaled lego realism. The union with Striker150 was the best thing the mod could have hoped for. The HUD is one of the coolest features, and is one of the best looking GUI add-ins I've seen in Blockland. The Zombie augment nodes, while not as desirable as unique player models, add an appreciable touch.
ZAPT is unpopular. I don't know where I went wrong or what I did poorly, but ZAPT is statistically used less than Gamemode_zombies and add-on developers like Phydeoux choose to spend their time developing content for it.
TL;DR: What needs to be improved? If I were releasing a v3, what would you want to see added/fixed/changed?