Creating some new units wouldn't be a bad idea, using custom models found on this site.
It would be better if you could choose one of the four races (or custom made/altered ones). Everybody is playing with the same units. The hero is the only thing that's supposedly different. There are many altered melee maps from which you can learn, here on the site.
Towers could be varied too. You could even create upgrades/abilities for them.
Would be nice to know which wave is the current one.
Players only get one hero that already has maximum level. That leaves hero/RPG progression out.
Items aren't custom. They're basic WcIII items. I suggest using your imagination and creating actual custom ones that serve different purposes.
The waves come one after the other without much relief. That forces the player to act quickly: train troops, build towers, manage the base etc.
The terrain isn't too nice. Why not add some more doodads, use various tiles and lower and/or heighten parts of it?
The Barracks trains Priests (from the start) but the Arcane Sanctum does too? The difference is the model, the attack type, armour & HP value but the description, icon and spells are the same...
Approved
(lvl 10+)
