I'm seeing is a lack of action in the screenshots though.
There are enemies in these areas. They're just dead.
Screenshots that display something going on (either through player movements or sprite presence) are generally much more interesting than ones that just showing the player standing in the environment. You said your level would use the Thunder Lakitu, perhaps you should've taken a picture with one in it?
The first pictures were more to showcase the aesthetics of the level. Here are a couple of quick screenshots with the Thunder Lakitu:
Also, I'm a bit iffy on the Layer 2 Palette in the first sublevel as well. It's mostly there because there isn't really a suitable night version of that background. A custom palette for that would definitely be nice.
Really neat level so far! You've provided the player several opportunities to explore, and your usage of the more "rare" sprites is very nice to see. I have a few small issues to point out:
Wouldn't it make more sense to have the hidden flower down here as opposed to before the poles?
I really like this puzzle, but it's very easy for a first-time player to screw it up and ruin the dirt bridge. Is there any possible way you can, at the very least, give the player more room to jump over the Chomp Rock (to the left of where Yoshi is in the screenshot)?
You've hidden clouds and 1-UPs in places most players wouldn't expect, which is great. I kind of expected something up here as well (it's the ledge right after the middle ring and you can only reach it if you perform a very a small jump off of the spring ball). Just a thought.
The third and fourth sublevels are finished, and the second has been mildly tweaked. I've also implemented SNN's suggestions. There's a pretty simple but devious puzzle thrown in there, too. The level is finished and 100%-able now, so without further ado, I present "In the Eye of the Storm" version 1.0.
I'm considering possibly offsetting the last room in level 50 down one screen so the top row of cement blocks isn't visible, but it's not really high priority.
EDIT: So I found a bit of an issue, fixed it, and figured I could also make a couple of quick changes I'd been thinking about immediately after releasing the last patch. New version.
-after skilift, I didn't know where to go. the pit looked like death. put an arrow or something to signify there is stuff down there.
-snowball gets very laggy with bombs & clouds.
-easy to despawn the 5-star cloud with 2 lakitus and a green piranha on the right side, maybe do a little better sprite management in this area
-neat snow theme and such but some areas like the sloped snow w/ snowmen felt a li'l dry / big open spaces, try putting a little more content to spice those areas up a bit.