We played this map in the imp today with a nearly full server.
I left a bunch of my feedback in voice and in the feedback plugin but I feel I can expand upon it hhere.
What you have here is a good base for a map, that is reasonably solid and fun enough. What you don't have is a flair to your map that makes it memorable and sets it apart from other maps. It feels like what you have is the bare basics of what would make a map work, but you're missing the everything else that goes into a full map.
My first suggestion to fix this is get away from making your buildings boxes. This, I feel, ties a bit into the point I will make below but even then. When you exit your spawn, this is the view the player is presented with:
You have three options from here. The main right in the enter is the obvious answer. You also can go left around the building (offering what looks like a height advantage). There's also a right route here, but it's less obvious to the player when they exit the spawn. This is good as it offers the standard 3 routes from the spawn yard that the ViaductFormula™ wants, but the main issue is that none of these routes really offer anything different in terms of attacking the point.
The left route immediately loses it's height advantage once you get over the bump, and you're presented with a view where the enemy has a huge advantage over your position. They have three main lines of fire at your position:
From the crate, which is a huge height advantage, from the point (where they likely are if they've captured it) and from the right. This isn't a very fun situation to approach into, and while jumping classes are given the option to jump up to the crate and gain some height over the point (something I found myself doing a lot), the rest of the classes seemed to end their combat here as they are slaughtered from the fire coming off the point or the plank above it.
Typically in KOTH maps, there's one "ground-level" exit from the spawn yard, and two that take a longer time, but attack the point from an angle and give attacking players a little bit of advantage approaching it. Think the two side routes on viaduct, or the side building (with the full health) on lakeside, or the farmstead roof in harvest.
Another issue I had with this left route is that it had no health making it even more dangerous to retreat and attack along.
Another issue I had with the spawn area is one that I feel extends to the rest of the map as well. Your architecture feels very boring and unexciting to fight around. Let's use my example of viaduct again:
Here are viaduct's 3 exits from the spawn yard. The main thing that makes this appeal to me over your map is that they are DIFFERENT. The left exit is higher, the middle exit is a turn to the left (which also helps optimization) and the exit to the right is closer to the spawn than the other two. The building that you cross isn't a big box with a big room in the middle, each route offers different geometry, with a different height level upon it's exit, different sizes.
I mentioned this in both the fb plugin and in voice chat, but your map really feels like it's lacking interesting geometry and art direction. None of the buildings feel like they have a purpose beyond offering height or a way through the map, there's no shape to the map outside of the gameplay spaces. If you notice on basically every official map, there's lots of stuff to break up the squareness of the playspace through extra buildings, pieces jutting out, alcoves in the wall...stuff that just makes the architecture feel a bit less like one big block. Detailing helps a lot with this, but even in alpha you can get this going.
Perhaps it's a bit self-centered of me to say but I feel making your map with a clear direction and idea of what it will look like and BE in the end ends up creating a lot more unique map with unique geometry.
As for the point itself; I liked the idea of the areas above that you could capture. The main issue I had with the point area itself is that there's only two small windows overlooking it, and they're directly opposite each other. This lead to a lot of the fighting taking place over the top of the point, shooting at small enemies sticking their heads out of a small opening. even widening this window so it was maybe 2-3 times as wide would serve to help this a lot. Perhaps lowering them slightly so they were level with the raised point bits would make people more inclined to use them as a way to shoot down onto the point as well.
Additionally, I feel a way for the enemies on the ground to attack these flanking buildings without going all the way around the building to climb the stairs (such a stairs in the building itself from the lower level, or some construction underneath the bridge crossing from the spawn-yard-building) would help make these buildings feel less impenetrable to the enemies.
In summary, I feel this is a good base for a map but you need to work on adding new and varying opportunities to the players in order to make it a great one.