Might depend on what you want to buy. For new they're OK, but they gets lots of returns and they reship these as new. I once looked a new B&W filter that had greasy palm prints on it, for crying out loud. B&H consistantly rates the condition of their used equipment MUCH higher than an objective observer would. this is particularly the case with large format equipment. Things I've seen them rate at 8 and 1/2, I wouldn't have given a "4". misrepresentation, in my book.
there are many good, smaller dealers in the NYC area with large stocks of used, professional equipment, with a 15 day return policy. It's nice to deal with the same person on the phone each time you call. I'll give you some names, if you want.
Jerry Pournelle, the Byte columnist and SF writer once coined "Pournelle's Law" --- "Never buy a computer from someone you can't get at with a baseball bat." I think this also applies to camera equipment.