Mammoth is a worldclass ski destination. With over 20 lifts and a gondola, there's something here for every level of skier/snowboarder. The major runs are groomed daily. And every year, there are improvements to lifts and operations.
The ski/board school is very good and organized. It seems like the instructors come from every continent. All are very good teachers with loads of patience. During light periods, you can get a private lesson at a group rate - a good deal!
The high ticket prices are also worldclass. It's a given that ticket prices increase every year even during the past recession. A ticket price of $100/day is getting steep and I don't mean the slopes. There are deals to be had through mammothmountain.com and 3rd parties such as Costco. Youth, juniors, students, and seniors can all get good discounts. However, if you are a middle aged adult, expect to pay full price. The ski school, while good, is also very expensive. At least with the ski school, one can rent gear at a nominal price. And as is typical for mountain resorts, the food is overpriced and underwhelming. But, the food is adequate to give you energy to finish your runs.
In the end you get what you pay for. You'll enjoy your experience at Mammoth in exchange for a lot of dough.