I finally got a chance to play this some last night on a Valve server.
Even having read the feedback here in advance and thinking I knew what to expect, I was disappointed.
As said already many times, the map really is too large; on a full server of 24 players I was almost always either seeing very few enemies, or very few teammates. It was rare to non-existant to actually have evenly matched skirmishes in any part of the map.
The teleporter seems mostly useless for anyone who isn't a sniper or sniper-wannabe, but its central location in spawn encourages too many people to use it.
There were several side passages that you'd enter thinking they'd go one place, but they'd end up twisting back around on themselves and dumping you out behind where you started.
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That said, I really liked the layout and dynamic of the area around Bots B. The ledges, stairs/ramps, water was a lot of fun to play in (was scout, soldier, pyro, demoknight at several points). There's an interesting vertical dynamic in this zone that was fun for jumpers, and even as a pyro I was able to make good use of the water area as an escape route.
In fact, the rest of the map was so annoying to play on, that I just focused on staying around this area because it was fun.
At one point, I'd gone the low route under the bridge, but round after round, this area (and the bridge) were pretty much shut down by minisentries (enemy team kept 2-3 engies in this area always after the first round). If it were a shorter distance to go, and had some cover from the area above, it seems like it could be a fun area as well. I liked the stair room at the end of the cave, the part that leads up to Bots A of the enemy base, but I was usually so badly hurt by the time I reached this area that I never could stay very long.