Hey, I'll make an attempt at reviewing this level.
I see you're new to posting levels in this community, but I have to say that you're doing well for a beginner. There are no major flaws in level design, stylistically it's mostly fine, you basically nailed the basics of designing levels. However, in the end, it's no more than average due to the fact that the level doesn't really try anything spectacular. There's one big section where you move from the left side to the right side, only once interrupted by a small cave section, and as a result, the level isn't very exciting. I'll go a bit more in-depth now:
Style:
Choice of graphics: The graphics you chose were fine and made sense together. Everything's in SMW style, with everything in the main section sticking to the same shades of red without having anything blend in too much. The cave sections worked fine too, although I'm personally not a huge fan of the rock BGOs used. The graphical style, overall, wasn't anything that made go "wow", but it's consistent and solid overall. 0.6/1.0
Placement of graphics: The way you positioned everything generally made it look fine. You use a lot of bushes and grass, but considering it's a forest level, I think the amount of BGOs used is thoroughly justified. However, there are a few places where there's minuscule cutoff noticeable:
There's also a place where you use sizeables, and the places where the tree BGOs overlap those sizeables it looks like you're walking in midair. It looks slightly off imo, so you might want to consider fixing that, although it's not that big of a deal. 0.6/1.0
Music: The music in the forest section is fine and works well with the theme of the level. The music in the cave sections works ok for in a cave section, although I'm personally not too charmed of the music an sich. Alas. 0.3/0.5
Gameplay:
General design: The way the NPCs are placed generally is alright, but rather lazy. Most of the level there's just 2 to 5 enemies following each other more or less in a row, which isn't necessarily wrong, but kind of a straightforward and "dumb" way to place obstacles. The bill blasters are generally positioned well, and so are the Banzai Bills, although the second one can be a bit of an issue if you're a player like me who just likes to go through things quickly. The placement of the Dragon Coins is mostly ok, albeit they're all very easy to obtain and I would like to have to do at least something extra in order to obtain them. The pipe leading to section 2, where one of the Dragon Coins is hidden, seems very random. There's no indication that that particular pipe leads to another section, especially since it functions as the home of a Venus Fire Trap already. The placement of the hidden block containing a 1-UP mushroom also is very random and can only be discovered by sheer accident. The placement of everything is mostly sufficient, but not very clever or interesting overall. 1.2/2.5
Difficulty and length: This level isn't too hard, with only a few jumps over some pipes being a little more challenging. There are no real peaks in difficulty though, so it's mostly fine. The level is pretty short, so maybe having a more expansive cave area or something else wouldn't have hurt the level. The placement of the checkpoint is fine. 1.8/2.5
Creativity and variety: This level's main pitfall is a complete dearth of creative level design. It does what it does well enough, but what it does has been done before quite a lot, you know? Of course, more inventive and original ideas come as you build more and play more, but a more seasoned player who plays your level won't find anything revolutionary. In addition to that, the level is very linear and only a small cave section with a few switches and a trampoline really adds another dimension to it. The level's like a piece of meat that's been cooked quite nicely, but it lacks seasoning, you know? 0.5/2.5
Overall, this level shows that for a beginner, you're entirely competent and you don't make any rookie mistakes. The level looks nice enough and plays well enough, but it misses a personal touch, something to make it stand out among the hundreds of SMBX levels available to us. I say with some practice, you're well on your way to becoming a very competent designer, though. 5.0/10