'tis promising
it is quite fun the first two times, but it's waaaaaaaay... too... slow... and you can totally autodefense with units. Increasing difficulty doesn't help much, because tougher enemies don't fasten it up anyway. If the game threw tons of these suicide bombers at you at some point before two hours mark it might have helped a bit.
Also, the 'Old Glory' doesn't work, unless it was intended to shoot pistol bullets with the delay of gravity cannon.