The focus on combat was probably not the best decision. If it seems a weird chose for a continuation of The Legend of Zelda, it's probably because Zelda II was at first meant to be the first installment in a new franchise. That doesn't mean the game was destined to fail from the beginning, but the questionable design choices undermine the result: the unfair difficulty, the roadblocks with almost or no hints (which are fewer than in The Legend of Zelda and that is definitely an improvement, but not a big enough one), the uninspired palace design (which end up feeling as long hallways full of enemies with no puzzle component involved), etc. Not a game for everyone.