Is this your first level? If so, it's pretty good! You've gotten the basics down pretty well, and it's certainly better than some other first releases I've seen. The level feels pretty good, and there are some good ideas here and there (the part with the cave and patches of grass on the floor comes to mind). There are a few things I need to point out, though.
-The main wall texture is almost uncomfortably bright. While these aren't your textures, it may be helpful to ask the artists to tone down the brightness, or you could just take the brightness in the level down a notch (like from 255 to 239 or so). Maybe this is something you like, though, so it's not much of a problem. The texture just hurts my eyes.
-Your water needs a few fixes. Firstly, it's much too bright. It feels strange when you jump into a pool of water and it's just as bright as the surface. Just take the brightness level down in your water control sector and you should be fine. Also, the water needs a colormap. This feature of SRB2 isn't really grounded in reality, as water isn't
really blue, but it really helps the feel of underwater spaces. Colormaps are something I used to have some trouble with in SRB2, so here's the wiki page to help you:
http://wiki.srb2.org/wiki/Linedef_Type_606
Lastly, this is personal preference, but I think water looks a TON better if its transparent. Not only that, but it lets the player know what's down below before they jump in.
-Your grass edges need pegging. This is kind of a community standard, really. I've found that a lot of new designers don't really like how grass edges look and can't be bothered applying them to every grass sector, but it's something that everyone has gotten used to, so it's strange for your level not to have them. It's ultimately up to you, though. As a side note: grass edges help differentiate platforms from the walls of the level in places with tall ledges, but your level doesn't seem to have those.
-Your music doesn't loop. Here's the wiki page (
http://wiki.srb2.org/wiki/Sound_and_Music_Tutorial) but it's admittedly not very helpful when it comes to explaining music looping. You should take a look at it anyway.
-You need multiple paths. Your level is already short as it is, and aside from some VERY easy to find powerups, the level has almost zero replay value. Some open explorable areas and path splits can go a long way. It takes a lot more work, but it's ultimately worth it.
-I don't like how you get spring'd over what looks like the thok barrier into the end of the level. It generally just looks weird, and there are better ways to transition from level to level.
Aside from all that, I think you've done a pretty good job for a beginner. Just keep working at the level and I'm sure you'll make something memorable.
