There's some usefulness of the monorail, although it's not the most efficient or accessible system.
I understand that it was underwritten by the casinos. Therefore, to get to the stations, you pretty much have to wander through the casino floors. Make people walk by the gaming areas. I get it. It just isn't terribly efficient and accessing (and finding) the stations from the street level is accordingly difficult.
But once you get past that drawback, it's a reasonable way to wander along all the casinos. Get a 24 hour pass and you can travel up and down the strip easily and check out the best places and restaurants. So if you're staying on the strip, it's a nice investment to keep you from walking several miles.
Or, considering all the buffets around, that may not be a good thing.