I hope you can forgive me for ignoring your level over the past month, but anyway, here we go:
In terms of visuals, you have improved a lot since you last level (as far as I remember, the original Act 1 was bland as hell. Those trees look great, and I guess they could be used a bit more as the rest of the level gets made. But then there are some major issues with the texture choice: It's probably just me, but I absolutely hate those outside wall textures. They are ugly GFZ recolors, and are used sparingly in CEZ for a reason. I'm somewhat unsure what you could use instead, though. The castle textures need variation badly. Those bricks tend to get boring and monotonous quickly, so you should mix them up with several other textures. One room that seems especially lacking in visuals is that outdoor room where both paths merge. It's fairly empty, and you should definitely liven it up by adding some scenery.
In terms of gameplay, you have some nice ideas, but some things don't work out as well as they should. The room with cannonballs is well-constructed and would play out nicely in theory, but for some reason, I only get hit if I stand still for over ten seconds, making the gimmick fairly useless. The room with the rising floors is a good idea as well, but I would suggest a different floor texture, since the yellow-striped one looks too factory-like. I also don't quite like how this room consists of nothing else than those actual platforms. This might be personal preference, but I would prefer if you put something more in there. I like how the zoom tube leads through a nice-looking room, but I don't like how the player has to spindash into the tubes to progress. It would flow more nicely if you let the player walk into the tube and spin them automatically. Also, the end of this specific tube screws up the camera a bit.
I don't know what's oil doing in a castle, but apart from that, I like the idea with the boxes. They should probably sink quicker and deeper though, because they don't actually provide a challenge otherwise. Teleports are also a very cheap way of forcing two paths together. It feels unnatural, and I don't think it would too hard to merge the paths normally. Also, the room you get teleported to is way too small.
On the other path, we also have some ideas. The rooms where you use the flamethrowers sources as stepping stones is really interesting, and I admire your effort for putting maces into a level, something few people have done until now. However, just by running at full speed, I can bypass that entire mace section without actually dodging them, so you should probably force the player to go through there properly. It's a pity if a gimmick gets wasted just because it can be skipped easily. Also, I can't help but fell that those maces are going through the floor, which looks highly unnatural. The rotating spikeballs after that need a wider radius, I can stand in-between them without getting hurt.
The short 2D section suffers from multiple issues. First of all, forcing a player to use a power-up is a really lame thing. What's the challenge of going through slime when it doesn't even hurt you? Just remove this Invincibility Monitor and make it water. Also, the platforms that crush against the ceiling can be ignored for the most part if you just keep running, making the whole section fairly pointless. I do like those caged-in enemies, but they are hard to notice because of the colormap. Another issue is the glitchy transition, which makes the game freeze for a few seconds somehow. The crushers after that feel weird because of the small gap between them. Put them directly next to each other to avoid that issue altogether.
I already commented on the room after that regarding visuals, but I also want to mention that those diagonal springs at the end are irritating and unnecessary. After that, we re-enter the castle and have to power an elevator. I actually like the idea of climbing on top of the generator, and I also like how the elevator sinks into the floor, but the way it is executed, it feels like a button hunt. The problem is that I have to go through the same area twice, feels extremely boring for some reason. Same goes for opening the door after that, but in that case, it's also absolutely pointless and adds nothing to gameplay. Simply don't put a door there and you're fine.
One last thing I want to comment on are enemies. I have the feeling that you put enemies in there just for the sake of actually having them. There are frequent issues with enemies disturbing the gameplay. This includes the left path at the beginning, where the Jetty-syns follow me, the death pit room where the paths merge (more Jetty-syns), the elevator (forcing the player to stand still and then putting Jetty-syns over his head is really bad design), and the button for the door (that Crawla Commander basically begs for attention). Another thing that bugs me are those two Snappers that come out of nowhere never to be seen again. They don't fit the theme at all and they serve no purpose. Everywhere else, the enemy placement is fine I guess, and it's not one of the more important aspects of a level anyhow.
All in all, this level has potential, I guess, and you already have some nice gimmick ideas. There are a few issues to be addressed, but mostly, this is rather solid. If the rest of the level will have some fresh ideas not seen before, this can easily become a good level. I hope you don't mind if I don't give you a rating, since I don't believe ratings are that important. If I had to give you one, it would probably be something around 6, but that's only a very vague guess.
Oh, before I forget it, nice amount of secrets to be found.
