The monorail is efficient, affordable, and easy to use IF YOU ARE STAYING ON THE EAST SIDE OF THE STRIP.
Remember, this connects MGM with the LVS casino. If you are on the other side (Bellagio, Cosmo, etc) you still have to walk all the way through a casino and cross the street. That is further than it sounds, and it is probably easier to Uber.
We stayed at the Flamingo during a convention at the Las Vegas Convention Center and it was awesome. Plenty of staff to herd people through, the online pre-purchase process was easy and quick. I really appreciate the value and it saved me a ton of time in taxi lines.
Use this service if you are commuting to a convention, travelling the east end of the strip, or plan to try and see all of LV over a day or two. It's a much better value than taxis. Don't bother with this service if you are on the west side of the strip or aren't capable of walking (there's still a great deal of walking with the monorail).