McCarran Airport is a busy place! Once you step inside the terminal, check-in is relatively simple. Since I travel a lot, I give this airport 4 stars for the fact that it has TSA Precheck.
Once you get to the terminal, the gates are pretty standard as far as convenience for a large airport, not great, not awful, but a-ok.
If you live locally, parking is pretty convenient, a 6-floor covered garage next to the terminal. It has been a while since I've rented a car here, but as I recall the process is more convenient than most considering the size of the airport.
Plenty of slots available to lose your money on as you wait to board, also plenty in baggage claim. What a racket! Fun though! :) There are also lenty of stores and places to eat.