Went 3 times with my wife and sons (ages 6 and 8). My kids got the package which included a full 2 hour lesson and equipment rental. They had a blast, and despite my older son never having skiied, he was on intermediate runs with the instructors by the end of the lesson. My younger boy tried snowboarding and was tired and frustrated a bit by noon. After lunch, we asked at the rental shop if we could swap out the board and get him some skis to try-- no problem, no extra charge, they were happy to help- but I never would have asked had they been busy then.
For my wife and I we loved it. Lots of good moderate runs for me who hadn't been on skis in 25 years, and my wife enjoyed it lots too, despite the fact that she has skied at Mammoth many times.
We went three times, from late Feb to mid March and only the first time did we have to turn back because of ice in the tunnels-- our front wheel drive only SUV wouldn't cut it so we just did snow play and hike that first day. Got lucky the next but bought snow chains and used them. Had to chuckle a bit at all the monster SUV's sliding all over the place-- only the chain crowd and true AWD or FourWD got up easily. But the parking lot is crowded of course and a pothole mess.
The staff was friendly all 3 times we went. Never failing to say "your welcome" everytime I said 'thanks' for slowing down the chair for my son and I to get on. Also, once my older son started down an advanced run by accident where it slips off from an intermediate run. I yelled and he stopped/crashed and a ski patrol guy was there to pick him up in less than a minute and get him back to where he needed to be. He was friendly, with no lecture or attitude, just doing his job.
Overall, a great experience all 3 times, and we are coming back with season passes this year.