I have only seen the Mother Brain battle via YouTube videos as I just never could figure out how to get too far in this one. It was a fun romp while I tried but ultimately I moved onto other games I enjoyed more like Contra.
Metroid certainly gave a lot of gamers some PTSD, this game was tough as nails back in the day, still is unless you memorized every little detail somehow.
RE: Have You Seen the Metroid HD for NES Release?