I have flown in and out of McCarran numerous times for various Vegas trips. It's a decent airport - security lines are fast and the Skycap outside makes checking in your bags much easier. This is one of the busiest airports especially on Sunday mornings when everyone is trying to get back from a weekend in Vegas.
I was a little peeved today since our flight was slightly delayed, but I got home safe so that's awesome. One plus of the airport, it has The Coffee Bean & Tea Leaf coffee shop. For a NorCal girl, this is the best thing ever.
So, expect long lines, maybe delays, fast security lines at McCarran.
Cheers!