A fantastic "Metroidvania"-style game. I'm a huge fan of 2D Metroid games, and this brings back fond memories of playing Super Metroid for the SNES.
The story is intriguing, but could have been tighened up a bit. There are so many characters that it all gets a bit confusing sometimes. Gameplay and controls are excellent. The improved graphics for this "Plus" version are straight out of SNES-era, and they're excellent.
Biggest flaw in this game is the length. The game is a bit too short. Certainly not as long as a 2D Metroid game. They could have added maybe 5-10 more hours of gameplay. But what is here is very well done.