Being a pretty seasoned traveler, I feel like McCarran is a very well structured airport. It's easy to navigate & I've never had to stand in a very long security line. Especially now that the new Terminal 3 is open, security never takes very long. The airport is always clean as well - even the bathrooms. All of my flights have boarded on time & I've never been stuck on the runway for a delay.
Of course, with all airports, the restaurants are notoriously expensive. And watch out for an older Asian lady who works at Burger King - She's a piece of work!