Best combat system of any metroidvania (of any 2D game I think), and some solid utilization both in bosses and enemy encounters. There's not much of a focus on platforming or exploration, but it works well as complementary to the combat. Higher difficulties don't just inflate the hp/damage, and while some bosses get worse (Dhistahn getting adds that you can't play proactively against), it's great fun going through with the different characters, on higher and higher difficulties, while S-ranking the bosses. Tons of customization and replayability, with several weapons/skill trees for each character, some freedom in order, and events that change the world map.