it can be rage-inducing at first, but once you get the hang of it, it becomes kinda easy. I prefer the 2d 8-bit like version and I'm not used to the three-dimensional environment of the new one. but other than that you can have your opinions when you try either one.
ok I don't know why you would need to know this but if you're already playing it, my strategy for the first boss is one or another. either stay in one place and dodge its bullets, or stay as far as you can while still being able to shoot it so that you have time to react.