Theme:
Originality: 8/10. I can't think of any maps with similar themes (Pipe is not the same theme, lol).
Creativity: 9/10. I really like this theme, it has a lot of potential and it's not something I would think of right away.
Build:
Attractiveness: 7/10. Although they are just plain cylinders, they look good. The water especially is a really nice touch.
Palette and variety: 9/10. Very grey, very nice. The palette matches the build very well.
Detail: 5/10. I would like to see more detail inside the pipes. The water and blank walls are fairly repetitive. Perhaps some mossy growth, cracks and holes in the wall, etc. This would be a way to vary the parkour a bit, too.
Parkour:
Difficulty: 5/10. This is undoubtedly an Insane map, but I think it may be a bit hard. If you don't want to nerf the jumps, I'd suggest adding some more checkpoints. The parkour was also at times confusing.
Variety: 9/10. One might argue that there could be more variety and depth with the parkour, but with this map I think the abundance of normal jumps and wall jumps matches perfectly. And there is variety in many parts.
Fun: 9/10. This map was really fun to play. The parkour matches and blends with the build very well and I love how it moves through the tubes. I also really like how you used white glass in the water, it stands out nicely.
Verdict:
8/10. This was overall a very good map. I think if you add some more checkpoints and improve the inside of the pipes, this would be hard to reject.
Good luck, and I hope you keep making maps!