Played multiple times on a full server and thought pretty well of it. I compare this to cp_steel since players get lost and confused with non-linear objectives. They did catch on after a while of back-capping D right away, which lead to a more enjoyable experience with more people learning the map (and properly defending).
I remember disliking the map at times after B, where it felt more maze-like and objectives were farther away from RED spawn. Compared to Steel where defenders have a reliable corner to approach a defending point, this was most noticeable on C located at a different wing of the facility. C felt weird to defend as an Engineer with attackers able to flank a Sentry from both angles.
Additionally, I saw a lot of empty space used for boring travel rather than combat, a problem I didn't see with Steel. This was most apparent on the A-C flank or the B-C side route, and I think this problem stems from the objectives being spread far apart.
I congratulate the design and originality put into Hadal.