This one took some getting used to at first. It has roughly all the same problems as the NES version (limited controls, and therefore odd ways of accessing your weapons), no map screen, etc, and in addition to those problems feels very “cramped”
I would have guessed that the lack of color would be what made the world disorienting, but that actually isn’t the case. Each area has a distinctive visual style, even in grayscale, and the music changes work well and communicate a sense of place.
After you get used to that stuff though, this game absolutely rules. There are no real “bosses,” except the final boss. You just go from area to area clearing out all Metroids. Only when you’ve wiped out all the metroids in one area, does the next area open.
It seems like the creators knew that this was a portable game first and foremost, so this was an early attempt at making it easy to “pick up and play.” That is, if the areas you can access are limited, you can play the game in short bursts and not have to memorize some giant world and hold it in your head between play sessions.
Apparently sub-3-hours is the time required to get the “good” ending. Wish there was some sort of indicator beforehand of my total time spent; I probably could have worked a little harder and achieved that.
For this play through, I did use a guide, and I think I found all missile upgrades and energy tanks.