I travel out of state via McCarran probably three or four times each year and I have never reviewed this place once.
It's best to get to the airport early to avoid long lines, especially the TSA lines, which can get ridiculous.
We usually fly Southwest whenever we go anywhere and their flights we take with them are always on time and they always have amazing service. Countless restaurants in Terminal C as well plus a Coffee Bean next to the tram station if you're looking for a coffee fix.
I try to avoid the bathrooms here as well, though they are usually clean. Last time I was here, I was in one of them and saw a giant hair in the sink that wasn't mine.