Agree with diveborg. I've been to Curacao a fair number of times. I stayed at Lions Dive once long ago when it was pretty much the only dive hotel option, it was ok but there are much better options now. The hotels to the northwest will do the better diving in the northwest. Also the area around Lion's dive is pretty built up and busy, which you may or may not prefer but in any event it does nothing to help the shore diving there. The shore diving is much better at the northwest hotels and sites.
I'm sure you would have fun on a group trip there, but you'd probably come away with a very different impression of Curacao and the diving there than you would staying someplace like Habitat, Sunset Waters, or some of the other places on the quiet west end of the island.