'twas alright.
I was kinda hoping for some variation on the theme rather than just another re-hash.
The problem with Space Invaders is that a) it's too monotonous b) it's been done too many times before, making it even less interesting to play and c) because so many of us have played it so many times, those earlier stages are just a bore to play unless there's something different going on.
Disregarding that, I didn't like the way you have the invaders start a little lower each time - once they start right at your defences, it seems a tad unfair when you get such a stupidly small amount of time to dodge bullets.
You can actually do high score on NG, btw (since from a previous review it sounds as if you may think you can't).