The gameplay here is a definite improvement over the first one. Same basic concept, with open ended towns, you have to find 3 passes and the exit.. but you can tell a lot more effort went into this one. The levels feel so much more varied and unique, not bland and samey like the previous game. There aren't as many hidden passages and 3D mazes, and there are more linear platformer-focused sections. And this game actually has boss battles, which the first one oddly lacked...
This game also introduces the wacky humor that the series is known for. A lot of houses have pointless dialog like:
"I bought Twinbee 2, The Goonies 2, and Gradius 2."
"Welcome back, hero of the tuna fish! To get to the next level you need... Ah, I'm in the wrong game."
"I am mystery chinese man. I tell quality joke. Straw hats past their heyday! ...You no laugh."
"I tell joke. A pun is its own reword. ... Why no laugh?"
"I tell joke no more. I am sick of life."