Not great.
The basic idea of the game was OK, but I really felt it needed some tweaking.
Once the slug moves as fast or faster than yourself, each level turns into 2 sections almost - flying, when you're dodging bullets, and on the ground, when you can do nothing but take damage and wait for the next level. The former seems too easy and the latter shouldn't really exist at all.
It is possible to get stuck at the top - I did so a couple of times, in the top-left whilst speeding up from the bottom right, but I found it difficult to replicate this. Not the worst thing - pressing up does bring you down, and at the start of the next level you're back to normal anyway.
Th graphics for th bg were a bit too simple imo. I really liked the tree - it had a lovely hand-drawn quality to it, with nice variations in thickness of line and a few bits uncouloured, but the grass/sky seemed almost a bit of a cop out. I would have loved the dividing line to be an actual sorta drawing of some grass, as your tree was, rather than just the line it is.
Also, a tiny bit of animation, specifically on the slug, would have not gone amiss. But I suppose I understand you just wanted to crank this out...
Music got a bit repetitive, although it wasn't the most annoying. Still, I found no on/off switch - a must in these kinda games.
Maybe if fuel (very) slowly replenished, if there was more than one fuel can per level and the slug shot more projectiles it'd be a great game. As it is, it's not.
The flying is just too easy and taking some damage after running out of fuel seems inevitable.
Btw, in a previous response to my review, you were mildly condescending, insinuating that I was talking shit re: high scores on NG. Just check out my 'dodging circles' game, for a quick example.