A for effort.
I think it's time for another one of my long-winded, hyperbolic rants with condescending pictures.
Last night we were talking about the first control point and the balcony looking over it, this upper area is not a viable sentry position for RED, which makes defending the first point rather difficult.
Engineers typically try to set up within the red areas, which on the upper floor is very open and very unsafe, on either of the side routes, BLU soldiers and Demomen can peek out and take potshots at the Engineer and all of his buildings. As Engineers tend to build their nests in such a way that they are positioned between their Sentry and their Dispenser, this can also lead to one side being able to step out entirely into the Sentry's view as the Dispenser blocks its sight. If the Engineer chooses not to do this, and builds his Dispenser further away, he exposes himself to either side and forfeits his ability to hunker down while being maintained by his Dispenser. Lastly, even if there are two Sentries on this upper area which can lock down both side routes, a Demoman can take the lower route and safely lob stickies and grenades upward without fear.
As for Engineers which choose to set up on the low ground, the pillars will offer them a minor respite with increased cover, but this position sacrifices control of all the height advantage in the area to BLU. BLU can drop as many Heavies and Demomen on top of RED as it takes to weed out the Engineers in this area.
Neither Sentry position at the first control point is as effective as the tower at the second control point, which is only a short distance away, but before moving on to the second point, I also wish to note that distance from BLU spawn to the first control point is unusually short, in comparison to official Payload maps, which may be a factor in allowing BLU to push so easily.
I like the second control point. There's lots of height variation for both teams and the big tower is fun to play on and around. That said, I feel the sentry position at second is a bit too powerful. There are three routes to the second control point available to BLU. The main route, through which the Payload travels, is the weakest, given its lack of cover and massive height disadvantage, while directly facing the sentry position atop the tower. The remaining two routes are on the same level as the tower's sentry position, but are much narrower, and one of these routes is one way, which locks BLU in a deathtrap more than it forces a commitment to pushing.
Irrespective of what team I'm on, I have an intense aversion to walking along the elevated paths on the perimeter of this area. The open space of the area makes them vulnerable to Snipers and the backing walls makes splash damage from rockets a significant threat. The tunnels below these paths area are long and featureless, which I avoid because there's little reason to travel through them.
What I would like to see in this area is the inclusion of a more significant structure, like the building opposite RED's spawn on stage one of Thunder Mountain, and additional cover for BLU to reach this building. This would allow BLU Soldiers and Demomen to flank the Sentry position on the tower without depowering it entirely as it can still defend two of the three routes available to BLU.
Coming up to the third control point, I don't really like this area because it's dominated by such a large gulf of a No Man's Land that is flanked on both sides by high platforms which BLU need to push the Payload through. Defending the third point is also tricky, as you must either defend from within this gulf or the thin strip of high ground which RED controls.
I'd like to see the scaffolding on the right become a more powerful Sentry position, which is harder to outrange and with greater ammo pickups, to make defending the third point less awkward due to lack of space. I would also add a flank in the caves, so that BLU are not always forced to fight in the No Man's Land.
The tunnel the Payload must travel through to reach last is rather difficult to push through, with it typically being stopped somewhere in the middle with no view of the final control point, partially due to the tight spaces, but also due to the two exits on the sides of the tunnel which RED can drop into and surprise BLU from behind the Payload's position. I think this tunnel would work better if the additional entrances and exits were closed off to emulate the tunnel before the first control point in Badwater or the roll forward zone at the final control point of Thunder Mountain's second stage, which allows BLU to push the Payload through the tunnel or down the slope with relative ease before stopping short of the control point and requiring a more serious push to close the distance.
Finally, the last control point does not feel very satisfying to defend as RED, largely due to the difficulty in doing so, which I believe is caused by a severe height disadvantage for the defending team. In addition to practically all height advantage belonging to BLU in this area, there is almost no height variation on RED's side of the field. Finally, much like when defending the third control point, the space available to RED is a small amount, due to how much of the finale is taken up by the body of water.
I would like to see the RED buildings at the finale expand, to take up more of the area and provide more of a defensive position for RED Engineers and Snipers to stand guard over the control point. Particular examples of this would be Badwater's finale and the final control point of the third stage of Goldrush.