Large gym that is well-liked and used by the surrounding community. Facilities and machines are several years old, but well-maintained and clean. Same goes for the men's locker room. The full-time employees at the front desk and independent trainers who lead classes are knowledgable and friendly. In almost two years I've hardly ever had to wait in line for a machine.
I see a lot of families coming and going, but kids are always in designated rooms or the pool, never in the main gym. Customers are a cross-section of the neighborhood, including a handful of body builders, some elderly people, lots of middle aged people and young professionals, and some college and high school students.
Students come from all over the US and the world to attend Thunderbird School of Global Management, which shares a driveway with the YMCA. T-bird students get a free membership at the Y and work out at all hours of the day.
The only reason for 4 stars instead of 5 is that it doesn't have the frills of a high-end gym, such as a juice bar, cafe, or spa.