My wife doesn't like going to museums with me since I generally like to read every plaque, poster, description there is. Luckily she didn't go with me since there is a lot of reading to be done. But there is also a lot of interactive and/or just visual exhibits so no need to be deterred if you're illiterate.
What I learned the most about was the origins of organized crime and that Prohibition was basically the catalyst for it taking off (yeah, good idea government). You also get to connect some dots with names you've heard of, to events, to times/lifestyles (early Vegas, Ratpack). Since this is in Vegas, I expected a little more on the Mob's involvement on the development of Las Vegas but there surprisingly wasn't too much on it.
Even I got a little tired of reading by the end and did a turbo-walk through the last floor (of 3). It's a little expensive so try to be old (senior), military, or local to get a discount (even then it's not cheap).