I pretty much like how Valve detailed Hydro.
It feels that the map was created when computers weren't that powerful and that developers was cheaping out on any detail that could decrease FPS.
Still, they succeeded - I like Hydro artpass, I like that optimisedly-beautiful views.
About gameplay - Valve did want not to create many maps 20% of which will be played. Valve did want to create a big map to hang out at, and made a mistake with the gameplay.
Actually, they thought wrong about 20%. Valve no longer make maps, they apply community ones. Simple, with easily understandable objective that is 1 or, more rarely, 2 - payload cart, current attacked point in A/D or symmetrical CP, the Hill to be King of. What I wanted to say - If Valve have actually seen what the game will be played like, they would not create such a big map with such a confusing gameplay.