Finally made it to the biggest of them all. It's sheer size and variety of terrain is as impressive as advertised. Everyone should be able to find a favorite lift and/or area here. We headed over to Blue Sky first thing in the morning via China Bowl, worked Game Creek Bowl before lunch, then after lunch finished up on the Avanti and Born Free lifts. Other than a little crud and ice in China Bowl, and near the Lionshead village at the end of the day, the snow quality was good and it was a great day of skiing. There are so many lifts and so much terrain to explore, that lift lines were almost never a problem.
As for downsides, the size is a blessing, but it's also a curse. Just getting over to Blue Sky in the morning is a chore unless you're capable of tackling Sun Up or Teacup Bowl, as the "wuss" route requires a minimum of four lifts from Lionshead to the top of China Bowl, then a bunch of skate-skiing along the creek at the bottom to the Skyline Express lift, OR three lifts and a tedious, crowded cat track named Sleepytime. Clearly the solution to this problem is to become a better skier. ;-) On the whole, average skiers are probably better served sticking to the front side, where there is plenty of terrain suitable for the intermediate wanderer.
Out of all the resorts we visited that week, I also found Vail to have the least friendly staff and clientele overall, which was not a surprise. I figure a lot of people go there just based on it's wealthy reputation, and so they can namedrop Vail in conversations back home.
At any rate, I'd come back, but probably not until I'm good enough to seriously spend multiple days in the Back Bowls and Blue Sky.