Initial fun and high hopes were quickly crushed by this game. The UI sucks: in-game menus show different values for stats than the upgrade screen shows, the upgrade screen "attack vs ___" stats ignore wizards (the most annoying enemy in the game), and the tower menu is an overly-bulky thing that gets in the way of the game.
Also terrible is the AI. For some reason the simple act of moving along the track confuses my guards into chasing after the first guy they see rather than shoot at the swords currently ATTACKING THEM! Besides that, the "catapult" units (they're actually cannons, so what the hell?) don't seem to get that moving forward is important, and will instead stand around shooting at enemies in far-back parts of the track, once again with unfathomable target prioritizing which leaves them getting hit by dudes they seem not to care about.
Balance: cannons are good against everyone, and their cost kinda makes up for that. But why the hell do wizards have so many damn hitpoints? As soon as they show up, groups of cannons have to spend dozens of shots to bring them down, yet again ignoring any weak and easily-killed melee units that may also be causing damage to the cannons or simply running past them to get into my castle.
So yeah, cannon strategies may seem like a good idea, but they're impossible due to shitty AI. The game had a lot of potential to be fun, but had terrible oversights and crappy AI that made the game unplayable.