Metroid Zero Mission is a remake of the first Metroid.
Story: The story in Zero Mission is the same as in Metroid but a bit longer. Samus Aran goes to the planet Zebes and fights the Space Pirates. The story is good and enough for an adventure-game like Metroid because it's more about the gameplay.
Gameplay: Like in any other 2D Metroid game you're walking through many different areas, kill aliens, try to collect as many items as possible and get new equipment. The areas are okay, not as good and creative as in Metroid Fusion but you like to see them. The enemies are well known from the other games of the series and nothing very special, even the boss fights aren't challenging. The thing that hasn't change is that there are almost uncountable hidden expansions for Missiles, Super Missiles, Power Bombs and Energy Tanks. Every time you get new equipment you want to go back and try to find some new expansions. The equipment you get is also known from other games but still cool. But unless in Super Metroid the enemies are not that difficult, they are quite easy most of the time.
Graphic/Areas: The graphic is good but the different areas were more creative in Metroid Fusion.
Sound: Ok the areas are better in Fusion but the sound is better in Zero Mission. Here you have the old one of a kind atmosphere with the great and simple tunes like in Super Metroid.
Conclusion: Metroid Zero Mission is a very good remake of the first Metroid game and when you play through the game then you unlock the original Metroid and can play it. The graphic is as good as in Metroid Fusion but the areas itselves are less creative but the sound is better than in Fusion. At the end I would say that Metroid Zero Mission is better than Metroid Fusion but can't really reach the masterpiece that is Super Metroid.