The units are so stupid and frustrating. They will casually walk into the range of enemy castles and towers. They will chase units across the map if you don't put them into defensive mode. If you do put them into defensive mode, they can easily be take out by archers without fighting back. They will open gates and let hordes of enemies into your town. They will stand there and continue cutting wood while an enemy army approaches them and kills their coworkers. The monks won't attack units unless you specifically order them to. Etc, etc. It makes parts of the game very tedious and unenjoyable.
The campaigns are similarly tedious. At first it's really fun and challenging, if you have the difficulty right. It's a challenge to figure out how to repel the big attacks and build up very quickly.
But after building up, it's no longer a challenge. And to win, you just need to spend an hour clicking through the enemies base destroying their structures. Even though you basically won an hour ago.
The multiplayer is terrifying. I tried it once and within like 10 minutes my opponent had surrounded my base with cannon towers and trebuchets. I haven't played it since.
The AI scripting is really cool. It's super simple to learn, very easy to modify other people's scripts, and very powerful. You can do a lot with just a few lines of their domain specific language. And you don't need any programming knowledge at all. And it's very extensive. There are tons of variables and functions available that let you do all kinds of things, and it's well documented.
But it's also extremely restricted. You can't do basic things like store variables, compare numbers, etc. There are arbitrary limits on how many conditions you can have in a conditional, how many lines you can have total, etc. They are workable, but I have no idea why they are even there. The only people modifying AI scripts in the first place are probably willing to accept if the game runs a bit slower because of all the extra code they put in it.
There's also no way to speed up the game. You only get "slow", "normal", or "fast". You need to use Cheat Engine to make the game run a hundred times faster. This is necessary for testing those AI scripts, or getting through those tedious offensive parts I mentioned above. They should have just let it be an option in the game.
Same with other variables like population limit, that's restricted to 200 for no reason. If I want a higher limit, I'll accept that the game runs slower. Just let it be an option, even in a hidden menu with a big warning or something. TBF, the new HD edition does let you go up to 500 IIRC.