We had it at work at a datacenter right beside offices and reception.

You just have to reinforce the ceiling panels and the windows so they don't get blown out, but it's not really an issue otherwise. It was all certified and regularly checked. Water is indeed a bit counterproductive as it's not really much better than fire for the equipment in there.

PS: Halon itself is of course gone but it's other less harmful gases these days.

What also happens is low-oxygen environments (they only raise the O2 when maintenance is being done).