Absolutely love this game. If you think the controls are bad that means you can't move a mouse. Press up to change target. Use lasers for stationary targets and missiles for moving targets. Replay some levels if it's two hard get your shields and power up. Overdrive varies by ship. First ship adds a big wave attack, the second recovers your shields and the third makes you invulnerable. Your right though the aiming system is different so if you like same old same old go somewhere else.
I'm sure people have told you but here are the thing I would like to see in the final game. Be able to cancel mis-clicked towers, the towers target the furthest enemy, upgrading towers is always good, and maybe add something between levels that you can level up your base and get small bonuses and such :) Can't wait to see the final game.