After playing this for a bit, I think I may have to say this is the best one yet. I really like the non-linear map setup. There are small treasure chests that hold collectable items and such or maps. When you select the game file, pick the 3rd option, it'll take you to a screen showing what you've collected so far. I've got a few maps, an orange spray paint can (I can change my color to orange now), and something with a music note (not sure how to use it yet).
I also really like that enemies now have energy bars. So, not everything takes a standard one-hit-kill, makes it a bit more challenging. For those complaining about the levels "going in circles", just take different paths when you find them. You'll eventually open up new areas and such. That main room will also be a warp to different levels when you find the warp rooms.