Without knowing the details as to what system is being used underneath (multicade is a nebulous term used to describe many different systems), I can't speak to the legality or performance of the system in question. The majority of equipment used in so-called "MultiCade" systems are as HarumaN describes, although some are different and some may even be legal.
For what it is worth, I have a couple of machines that could be classified as MultiCades (including a 48-in-1 and a 60-in-1), including one at my vacation property.
My kids love them ... which reminds me that I need to fix the one at the cottage
... but it could well depend on the age of the kids and their interests.
My kids (7,9,9) love the classic games, so it works well. Some older kids in the neighbourhood don't like them so much and gravitate to the video game consoles.
A while back I saw a webpage that talked about the legalities and managed to find it again:
http://www.bmigaming.com/multicadegames.htmI am not recommending the vendor in question, nor confirming their advice (although I don't see any facts that I can disagree with) ... it is just a summary written in plain language that speaks to the point.
Good luck and
to your boss for considering getting an arcade machine for his kids.