This game (well the very first SotB game) is what made me buy an Amiga 500, back in 1991. The guy had a few other games we played: Xenon II, Menace, Blood Money, and some 2-player tank game that was pretty fun but I can't remember the name.
Anyway the first Beast game had pefectly smooth scrolling with lots of parallax layers, big sprites, and a that beautiful soundtrack with pan pipes. Had never seen or heard anything like it before.
The controls are pretty rough by console standards though. It's up to jump, and just the one fire button to attack. Pretty typical for computer games with joystick back then. If you want something easier, the Sega Genesis game is pretty good, but doesn't quite match the graphics and sound of the original.
Anyway it's a pretty tough game. Made it to the bottom of the castle level without cheating, and no further. It's pretty easy to get ganked in this game. You kind of have to memorize patterns and stuff, like in Ninja Gaiden.
Anyway the game was impressive then, but maybe not as much now for someone who's seen even better stuff on Neo-Geo and such. I still like its weird and unique atmoshphere. Some other good Amiga games to try: Gods, Satan, Leander, Risky Woods, Lionheart, Toki, Prince of Persia, Another World, Flashback.