I haven't played the map, so this feedback may not be great, but I have some suggestions to offer based on my experience with similar types of maps. Hopefully it will at least give you some things to think about.
First of all, it's a solid design with the potential to be even better. Even without reading the description you've given here, it was quite obvious that it's inspired by Zealot.
I don't have XBOX Live, so I'm not able to actually edit your map and link you to the changes. So...my next best option is to paint you a picture, lol.
As you can see, my feedback is going to be completely focused on the corners of your map. This isn't too surprising since most arena maps are designed with the main focus being on the bases and the sides, the next focus being on the middle of the map, and the connections between the bases and the sides being usually the last thought. Ironically, these connections/corners are generally the areas where the most action takes place.
Starting with the bottom corners...
The darker blue area is unnecessary. The only reasonable purpose of it is to provide cover for players spawning in those corners, but there are better ways to accomplish that.
The first possible solution is to replace the dark blue area with an elevated platform. This would give spawners some protection without totally segregating that corner from the rest of the map. It should be placed at a height that would allow players to jump on top of it though, preventing the 'hide and seek' games that sometimes result from the structure you currently have there.
Another possibility is to just completely remove any structure from that dark blue area, then give spawners some protection by creating a pathway around the outside edge that's at a lower elevation than the rest of that area (light blue). Doing this would also allow you to pull those corners in closer to the middle of the map. There's not exactly anything wrong with the size of the bottom corners. However, the large spawn influences at play in Halo 4 can result in players repeatedly spawning in the corners of maps like this, and almost never spawning in other areas of the map. While it may seem counter-intuitive, pulling the corners of a map in can actually improve spawning since a spawn point around bottom mid may now have a higher likelihood of being used. I know this isn't a great explanation, but I'm trying to prevent this post from turning into a novel (rather unsuccessfully, lol).
On to the top corners...
My goal here would be the same as it was for the bottom corners; pull them in closer to the center of the map, and reduce segregation. The genius of a map like Midship lies in its ability to allow players to spawn relatively safely without using walls to
completely block spawning areas off from the rest of the map. I'm not trying to suggest that walls can't be used to create safer spawning and safer travel routes, but on an arena map they should be kept to a bare minimum. This is where Zealot suffers in comparison to Midship (in my opinion). I think you can utilize some of the ideas presented in Zealot, while also eliminating some of its negative attributes.
The basic idea I have is to take the yellow section and move it to the area I marked red, connecting those two platforms. You would probably need a small bit of cover at the green area.
Then, I would take the whole purple area and bring it in closer to the middle, occupying the space where yellow is.
I know it wouldn't be a simple change to make. It would require a pretty major redesign to get everything to connect properly. It's just what I would do if it was my map.
