I'm not a big fan of M&M's but that store proved me wrong. Four levels of M&M stuff seems extravagant, but we're in Vegas and why not? I found myself being like a little kid again, going through every level to see what they had.
Bonus points on them having items that were totally affordable! They have everything from shirts, sweats, erasers, golf balls, etc. I got super excited because they the limited edition Raspberry M&M's! Those things are like crack, I swear.
The staff was super friendly, despite it being chaos in the store. Even if you don't like M&M's, it's a cool place to visit.