This was one of my fav CS maps, is really is coming close to a killbox so maybe if the walls were changed to rocks then maybe it would look better.

Not quite a killbox, but close.

I think it will serve though, cause one of my favorite HL1 maps was Xfire, and it was a box filled with stuff.

Careful though, cause it really is close. :/

I suppose if it's a remake then it should be exactly the same or have a bit more added.

Hmm it looks like a giant sandbox. There are some nice parts (the bird and the sun, the pipes coming out of the water, some of the architecture near the walls) but overall it does feel very very 1.6. Perhaps you could use more curves to break away from the CS1.6 feel.