Gets a bit annoying after a while but it's a fun way of killing a few minutes. I'm a huge Bubble Bobble and Rainbow Islands fan as well, BB still works great but Rainbow Islands hasn't weathered so well, difficult to control for some reason. I used to be a total gun at that game on the Atari ST.
Same, Parasol Stars whenever I get a spare moment. Was playing Sonic 2 last week, so fun.