Wowie gee, this was interesting.
Goods
You stuck with the theme the entire way through: a SMW forest level with poison and switch-block rides. Using the NPC switch blocks is great on you, because that's something you rarely see. Your NPC placement wasn't bad either. You had good background placement as well.
Bads
Your coin placement was not good, as most of it was just set on the ground. You also only had three Yoshi coins, when there should be five, maybe more. The Wigglers were just a Rex, and you could just stomp on it twice, when normally, the angry Wiggler cannot be killed by just jumping on it. Doing so will make you just bounce off. This isn't exactly a major complaint, though.
One big complaint is the poison. It doesn't look good in the level. Emphasis on the word look. I am all for using poison in any level (with some exceptions), but it just doesn't look well with the level. It
looked out of place, though it did not feel out of place.
The propeller-flamethrower section was nice, and I don't have any complaints about it being short, honestly. Though,
the last room in that section was a bit cluttered. The vines here and later in the level had cutoff as well. Those two bridge pieces also cut off at the bottom.
The next section was a pretty cool concept, though it was not executed greatly. Still I had fun, except for
this little part at the end. My first time playing, I never suspected that hill would have killed me. Not to mention the next attempt, I tried to jump to the platform, but it fell into the lava. I felt that small part was a little cheap. The fact that you couldn't see the lines which the platforms rode wasn't bad for the level, though that part at the end needed it. To fix that, just give a warning of some sort.
The next section was a chase-gimmick, where you would hit a switch and run away. One flaw here: you can not be chased at all if you want. You can just hit the switch and let the poison go by you, as long as you were in an area where you could not be hit by it. I actually let the poison chase me, just to see how it would go. The first one never stopped. I can see what you did in the editor, but for the Stop 2 and Stop 3 event, you forgot to set the layer to move. If you had done that, it would stop. Though, due to the way it was designed, this wasn't much of a flaw for either chase-areas. The first chase-sequence was pretty good, but the second was way too crowded and difficult if you chose to be chased by the poison. Also, in that section, the block that showed the Yoshi coin should have hid itself after being hit.
The final section was pretty basic, no complaints there. It was a bit interesting to see a warp-exit, though. Rarely seen. One thing I just couldn't fit in the review is that you have only wiggler-critters. More on that in a bit.
Unused Content
Something that's always fun to see in a level is the stuff that went unused. Now, the Wiggler in the level was a Rex. However, there is a normal Wiggler replacing an SMB3 goomba, killed in one hit, obviously, and there was an angry Wiggler replacing the Bully. You had Monty Mole and Swooper critters, which really should have been used to give more life to the cave-sections. There was an SMW Bomb-omb replacing the SMB2 Bomb and Bomb-omb. Probably just an unused enemy.
There was an unused Buzzy Beetle, which would have gone well in the cave-sections. The SMW Beach Koopa/Blue Shell Koopa without a Shell was invisible, no clue why.
Finally, I think an entire section was scrapped. There was a SMW-floating platform in there, but it had really weird AI! It would leap to the right, into the death barrier. No clue why that was. Though, it might have been used for an unused cave section, which Section 6 (section 5 was the final one) had cave music. He put a pipe there to end the level, but it would originally lead to the cave section, though he felt the level would just run on. Just my two cents.
Score
I'd give this a 4.5/10 or so.
Great idea(s) for a level, just not executed well.
I don't really intend to change it either haha
