8-12 Players Ring (working title)

Warning: Huge wall of text incoming...

Here are a few things you can do to improve this map, and also apply to any future projects:

Clean Forging - Aesthetics are certainly less important than functionality, but they also play an important part in the 'immersion factor' that determines whether players feel like they are playing in a real locale, or whether they feel like they're playing in a lego land. There is some room for improvement on this map.
In the first pic, the Station Corridor is protruding through the Brace Large. On the Ramp Bridge piece right next to it, the railing extends into the main walkway. Pull out the Brace Large to cover up the Station Corridor. Turn the Ramp Bridge piece over so that the railings are on the bottom. Also, on the last pic on the left side you have a Brace Large going down, and then a Stunt ramp going back up. You can just extend the flooring of the lower level until it merges into the Brace Large. These are just a few examples of areas that can be cleaned up which will result in better looking map.

Angles - Particularly in the corners of your map, the transitions would feel smoother if you replace the 90 degree angles with 45 degree angles. In general, it's good to avoid using 90 degree angles as much as possible since it greatly reduces the effectiveness of camping near corners. Unless of course you are building the map with close quarters combat as the main focus, in which case you should use as many 90 degree angles as possible, lol.

Thin Walls/Floors - This is part of the immersion factor that I mentioned earlier. Using thicker pieces for walls and floors makes them appear more 'real'. I'd recommend using 'Thin' blocks less, and 'Short' blocks more often.

Cover - The best way to create cover is through the actual structure of the map. This is done reasonably well on most of this map, however there are a few areas where pieces are placed simply to block lines of sight, and otherwise have no apparent reason for being there (they don't look like part of the map). The vertical Brace Large in the last pic is a good example of what should be avoided.
Also, try to avoid placing cover in the middle of pathways. Players should feel free to move through main pathways without having to avoid structures in the center of those pathways. Such structures can have a negative impact on the flow of a map. The Station Consoles in Purple with the BR and Plasma Grenades on them are a good example of this.

Top Mid - It is too powerful of a position right now. The wall double's offer too much protection. With the large size of top mid, very little cover is needed. The flooring of top mid itself is a form of cover, since players can just back away from the edges and nobody below them will be able to see them. The fact that there are no hard routes (ramps) to top mid only makes it more powerful (harder to get there, but easier to maintain control of once you're there). To better balance top mid relative to the rest of the map, you can either simply remove almost all the cover, or you can eliminate the bridge pieces around the perimeter and create some hard routes up there.

Weapons - I generally prefer fast spawning weapons. In this case they may be spawning too fast, though. I would also change up your weapon timers so that each power weapon will spawn at a different time. My recommendation would be to set the respawn rates at 2 minutes for the OS, 2 1/2 minutes for the Sniper, and 3 minutes for the Rockets. Using these times assure that both teams will be focusing on each of those power items every time they come up. When you have two power items spawning at the same time, each team can grab one of them uncontested. Traditionally, power weapons and powerups have been used as a means of creating conflict between teams. Having 2 power items spawn at different locations at the same time goes against this principal.

Disconnectedness - I do have one major concern with this design. The Hybrid of a few different maps is an interesting idea and one that can often work. Right now, however, the purple side of the map feels very disconnected from the rest of the map. It almost feels like a different map altogether. My personal suggestion is to pull it in closer to the rest of the map, and to eliminate some of the walling that is currently separating it from the middle portion of the map.

Finally - I hope this feedback will be helpful to you. All of the things I've mentioned are fixable, or can easily be applied to any future projects. If there's anything that's not clear, just let me know and I'll do my best to clarify it.