First of all, kudos to the design team in Mario for going with a creative world design with unique area themes...instead of having the generic water world, ice world, desert world...etc.
I've never thought about it before, but it's not normal for a Mario game to have an entire world set in a forest. It's one of my favorite sections, thoguh
The person upthread who said that the graphics and music suffered a little in the transition to a GBA cart wasn't kidding. I haven't noticed a huge change in the graphics, but the music that is so great on the SNES version suffers greatly. I do like that they give the player the option to play as Mario and Luigi, though, even if Luigi has sort of wonky controls.
This game, along with SMB3, are two of my favorite childhood memories. I was one of those kids who would beg my parents to take me to Toys'R'Us just so that I could play SMW on the demo kiosk that was there. During those few weeks before the SNES came out, there was always a line there. Mario Madness was in full swing.
At the time, I was amazed by the music and the graphics effects of the game. In particular, the Ghost houses (with the transparency tricks for the clouds and ghosts) really stood out at the time. I don't think that anything quite like it had been done on a console up to that point.
It's perhaps inevitable that this game is compared to SMB3 since they share so many elements and gameplay features. While I prefer all the cool power-ups that SMB3 had to offer and some of the cool settings like the airships, I've always found this game to be easier to pick up and play. I think it comes down to the feeling of freedom, speed and control that the I get when playing this game. I've always loved that you can kick shells up in the air. I like all of the new attacks that Mario has (the ground-pound with the cape, punching through the fence, etc., Yoshi shell power-ups). Also, in general, SMW just feels faster than SMB3. Mario accelerates more quickly, and, and it's easier to change directions in mid-jump.