This hack has been worked on for over 9 years!
Samus' suit is redesigned, all of the maps have been edited, title screen, mission text, credits, and item locations.
None of the weapons or power ups were changed. The author believes the original Metroid nailed it, and choose not to change them.
It includes Saves and a Mini-Map. The mini-map does have problems when you get to the edges of the world. Once you're back away it works like normal.
Here is a link to a demo play video ---
Metroid (U) [!].nes - GoodNES 3.14
CRC32: 4DE6A02B
MD5: D7DA4A907BE0012ABCA6625471EF2C9C
SHA-1: 166A5B1344B17F98B6B18794094F745F8A7435B8
SHA-256: C5EEA06E1E1128B576BD789F1A4F63BB154D6D31579C2F319382FB77A72D34A6