Almost awesome...
...but still purely a turret defense game, where you do nothing but control where the turret points.
Don't get me wrong, what it does, it does awesomely well, but it could use something to distract from the wave upon wave of black, silver, gold bad guys. At the moment most of the variety comes from which enemies stay what distance away and how much it hurts if you let them shoot, the best enemies were the ones that circled your base, set up their guns, and unleashed while you tracked and shot them down- because they were interesting, and not common in defense games. Same for the huge blockers that just rolled up and got in the way while the artillery blasted you from behind, they were awesome because they were interesting.
If you set the enemies to come in waves that were choreographed beforehand- for example, send a couple blockers in front, followed by a pair of troop carriers (full of the long range soldiers) and small artillery. Or send in a couple dozen of the ninjas to distract from the mega-artillery rolling in from the sides... it's just "throw everything at the turret and see if he can shoot it all down".
If the guns did something other than all fire in generally the same direction, hit and do damage, it'd add strategy to how you built up your weaponry. Say if the cannon made explosive blasts when it hit, the lasers penetrated through, the flak cannons spread out shotgun-style instead of just at an angle. Maybe some auto-defense turrets you could fit on top, or a bigger battlefield where you could attempt to mount other turrets, develop a base, and cover more area.
More criticisms;
1) upgrade screen is fugly, it looks rushed unlike the rest of the game
2) even with 7 tracks, the music starts to grate- if they were more ambient and less prominent, it wouldn't so much
3) no way of seeing your damage that you inflict other than watching your shots be absorbed
4) no visible signs of wear and tear on the turret itself at low health
anyway, that's me being hyper-critical. i know a shit-ton of effort went into making this, so you'll want #2 to be the best possible.
5/5
$0.02