Very good
Game is very true to the metroid series.
This game can even be partly sequence broken by getting the speed booster, and then using it over the gap by your ship. you then run to a room that can normally only be gotten by space jump boots (a8). However, with the speed booster, you can use the raised area in the next room (a9) and jump to get to the next room. If you do do this, you need a decent amount of health, as there is an enemy on that ledge as well.