W.I.P. Floating Gardens- Original

First of all, the map needs to be build on the MinecraftBuild server on Brawl's network for it to be considered, not in a singleplayer world in a file. A guide on how to use MinecraftBuild can be found here: https://www.brawl.com/wiki/build/

Aside from that problem, it looks absolutely wonderful, props to you for that.
Now, aesthetics shouldn't be the main focus of a map. Gameplay is more important for a map to be selected for testing (though looks still matter).

Some gameplay issues with your map:

1) The map is too small.
If there are 5-10 players on each team, this map would suit them well for its size. However, if there is a full server on during peak times, with 25 players on each team, the map would be extremely crowded.
For a reference of how big a map should be approximately, I believe Blackout (/map 424 on MinecraftBuild) is the smallest map currently in rotation. It's about 150 by 150 blocks, and it's wide open. For a full game, that size suits it pretty well for a 5 capture map.
This "small" issue prevails through the majority of these suggestions.

2) The map is primarily paths, or "bridges" in midair.
Now, referring back to the previous point, Blackout is wide open with ground pretty much everywhere. Here, the majority of the map appears to be pathways in midair, with no "base" easily identifiable for each team. The problem with this is camping these paths, with Engineer turrets or classes that deal large amounts of knockback to knock people off.
The best comparison I can make to your map is Halo (/map 138168), with pathways in midair from one base to another. Halo already has many issues regarding these bridges at the bottom of the map, with Elves using Wind Element and Mages using Lightning Spell to knock people off them. However, on Halo, there is a large base on each side, and while a base doesn't have to be nearly as large as that one, there should be an easily identifiable structure. As well, Halo has a large area up top where it's not so easy to get knocked off of, at the cost of taking more time to get from one side to another.
I would recommend either making wider paths, or adding some platforms in midair so it's not only paths.

3) The paths are too narrow.
Speaking of narrow paths, they should be at least 6 or 7 blocks wide and even then it's still cutting it a bit. Again, Halo has these problems. Putting fences like you have done at some places on each side does sort of help, however, it turns the path more into a headshottable tunnel, making combat difficult there.

4) The Flagroom.
There are only 3 entrances to your flagroom, all are very narrow paths. This is not a good idea, as one ninja camping each entrance would be enough to knock someone off and into the void.
As well, the room is way too small, making it hard to get in and out for a clean steal. However, this isn't really that big of a problem, as maps like Blackout and Castle Cavern (/map 1575) have small flagrooms.
Also, a good idea is to make it so that there is more than 180 degrees of entrances. What I mean by this is not to have a back end of the flagroom where it is very, very easy to see all entrances and some of the path leading to it. This gives too much time for the defense to react and kill, making offense hard.
Perhaps you could add a back entrance or a top one and expand the room, but not too much.

5) Spawn.
Spawn should not be enclosed and small, and should have more than one entrance out. It's not too easy to see from the screenshots you've given but it appears the building at the top is spawn. If it's small, then spawn camping could be a huge problem, especially with only one narrow exit onto a narrow pathway.
Another problem is that it's too close to the flagroom. If an assassin or ninja were to die on defense, they could quickly get back to the flagroom and deal more damage before the offense can escape. It's more of an issue with assassin, as they get their instakill back and can easily clear a flagroom by attempting over and over in a short period of time.
Add more exits, and expand it a bit. Move it away from the flagroom.

6) Restrictions.
Maps should have restrictions for placing structures like Turrets and Mob Beacons. A tutorial on how to configure your map can be found here: https://www.brawl.com/threads/66899/

That's pretty much all I can think of for now, good luck!