This is a fun one. The first Adventure Island on GB did a good job of correcting some things in the Adventure Island formula, which is a game I never particularly liked because of its repetitiveness, slide-y controls, and... well, that's mainly it. Many of these problems were cleaned up in that first port/remake/whatever it is, but the game still seemed to lack a distinct soul that it could call its own.

Adventure Island II GB now gets to work on that part. Sprites have been enlarged to show off nice graphics for a GB game, the music remains good, and the structure of the game has been improved, moving to a sequence of levels on a world map that have connecting shortcuts that can be entered via secrets in the levels... there's a lot of nice new stuff here over that iteration.

Something about the Adventure Island gameplay formula still just seems... a little jank to me in a way that's hard to describe. Jumping doesn't get a lot of distance. Your projectiles lobbing towards the ground is annoying and causes easy accidental misses especially with certain types of enemy patterns. It's still got problems with the protagonist sliding all over the place.

But still, I have to designate this one as "good," because I enjoyed it, and was engaged throughout. I especially like the new boss fights with more detailed sprites, even if the patterns are pretty simple. All in all this is probably one of the better OG Game Boy games out there as far as I'm aware. It feels a little sad to say it, though.