I just went through it first time on retro. I felt most of the game was pretty fair and pretty well designed, if you took your time. I went through the stages from left to right, top to bottom. I had used up about 2-3 of my continues before reaching the last stage, which is where the game just turns to complete BS. I was having a good time until then...the last stage ruined it for me. Every single part of the stage is designed to be cheap death. It took me 5 lives just to make it past the first screen. I finally made it to the final boss with about 4 lives, 0 continues. I of course died because he's ridiculous just like the stage before him. I said **** it and just watched the end on youtube.
Don't know what the dev was thinking with that last stage, but the rest was pretty good.