Hey, pretty decent level you got there! There's a few things about this level that I like quite a bit, but there's a few subpar moments and stylistic inconsistencies that hinder the experience for me.
Choice of graphics: I really liked the darkened canyon tileset coupled with the cacti. In general the outdoors sections looked great, all the graphics fit well with each other. The ghost house tileset and enemies I was less charmed of, mostly due to the fact that the grey Boos and Eeries in particular blend in with the blocks and the background. I understand why you decided to make all of them grey, but if you follow through with that decision, at least make the enemies lighter so that they don't blend in too much. Also, you might want to consider just recoloring the ghost house tileset, enemies etc using colours on the SMB3 palette and using SMB3 versions of the enemies , blocks, and items where possible, the discrepancy between the SMB3-styled canyon and the SMW-styled ghost house feels a little awkward to me. 0.6/1.0
Placement of graphics: The outside sections were decorated nicely. Enough BGOs to look good, but not so many that it became overwhelming. The ghost house sections looked a bit more boring, but I suppose that is to be expected, since there aren't many ways to make a ghost house look pretty anyway. My only real complaint is that the mountain sections and the ghost house sections weren't very coherent together, it's basically just a slightly darker canyon level that suddenly turns into a ghost house. Simply adding some Boos to the mountain sections could hint at the "ghostly" part of the level, it makes the transition to the ghost house less sudden. 0.8/1.0
Music: Didn't like it, plain and simple. I guess it fit the mountain sections to a degree, but it seemed misplaced in the ghost house sections. Try finding two pieces of music that fit better in a video game and that fit mountain and ghost house, respectively (and make sure they're not too different from each other, so basically not something like a chiptune paired with some orchestral work). 0.2/0.5
General design: The design of the mountain sections is mostly good, with only section 3's abundance of Lakitus being somewhat annoying (I'll get back on this later). My main problem involves, again, the ghost house. The gameplay here mostly consists of a bunch of fake doors leading back to the starting point, with one hidden door triggered by a P-switch (yawn). This kind of ghost house gameplay simply isn't fun, it's just a bunch of trial and error (made more annoying by the fact that you have to remove the coins around the door before pressing the P-switch, or you have to get back for another switch, which is boring and frustrating). It's tolerable the first time around, because there are only two or three fake doors, although one can only be reached after pressing the P-switch and therefore it is frustrating when you think you're entering the right one and then it turns out to be false and you have to go through the section again. the second time around, however, it's hard to tell where the door will be. I just don't like this kind of thing. Further general comments: the placement of the Dragon Coins was good, the placement of some random Munchers in section 3 could be a little annoying (especially because they aren't all that noticeable, so you'll easily walk into one by accident), and there might have been a little too many powerups for such a short level (why were there two powerups so close to each other in the second ghost house section?). basically: mountain good, ghost house not so good. 1.5/2.5
Difficulty and length: The difficulty was mostly on point, with section 1 being pretty intermediate in terms of difficulty, only spiking a little towards the end of the level with all those Lakitus. Remove a few of those, maybe. The aforementioned powerup spam also might have made the level a little easier than it really should have been. The ghost house sections were mostly difficult because an Eerie or two caught me by surprise. In terms of length, the level was pretty short, and I feel like you could maybe have expanded a bit on both types of sections, since the mountain sections still had some untapped potential imo and the ghost house sections just weren't up to par, feeling way too short if you knew what you were doing. The ghost house just needs a redesign in general if you ask me. 1.7/2.5
Creativity and variety: The combination of a more regular level and a ghost house (as flawed as the execution may be) is a pretty cool one, and it was mainly this idea that made me want to play it to begin with. Another compliment should be given for the Lakitus that hover on their place, turning them into pretty unique enemies (you could have spread them out more evenly over the level, though). Individually though, both the mountain and ghost house were pretty standard in their execution, and the ghost house especially felt way too mundane. With some more effort put into it, you could probably give it more of a unique spin, so that the player doesn't have to do another pretty boring hunt for the P-switch that has been done before to more success in the past anyway. 1.5/2.5
Overall, this level is fine, with its flaws being balanced out with cool graphics and an interesting concept. I mostly see a lot of untapped potential, though, and I would love to see a level in the future that successfully pulls off a combination of level styles like this. 6.3: pretty good.