This game is a smörgåsbord of all things I love about Konami during this era: fast and tight movement, great variety with a couple of shoot 'em up levels mixed in as well as a boxing duel between two giant robots, great bosses that sometimes have multiple forms or phases, great audiovisuals with some humorous touches, and near technical mastery of the system all in one package.
The jetpack, while implemented slightly better in later games, is great fun to use here as well and sometimes makes the game a contender for the fastest playing 16-bit game if you know the levels well.
By the way, check out Screw Attack's Retro vs. Reboot for a laugh.