I'll start by saying that I think the visuals are held back heavily by the inconsistency between background and sprite pixel sizes - the tilesets, enemy sprites and the boss turned out really polished and consistent by themselves, but the pixel sizes for backgrounds and dithering effects were all over the place and very noticeable, so it left a rougher impression overall.
Controls took some time to get used to, but it's not really a problem - though as Michael mentioned in an earlier comment I think replacing the instant acceleration of some actions, like turning and jumping, with a very short gradual acceleration would help out in making movement feel more responsive.
As for the positives - the game has a fun flash-era vibe to it, I was startled by and chuckled at the out-of-nowhere swearing when you die. I also liked how "bullet time" was quite literal, that one was pretty slick