What to say at this point, is a masterpiece of the genre. Incredibly well designed (both its areas, bosses and combat), enterntaining, intriging, really scary in the areas with E.M.M.Is (especially in the beggining) and the sensation of progress is the best in the series (at least in the 2D games, that is). It's an absolute gem, one that has to be remember as one of the crown achievements in the metroidvania genre, and a miracle that it ended up being a reality.