It just so happens that I have been taking my ski vacations at Mont-Saint-Anne for the past 5 years, so I can give you some info.
The first thing you notice (during weekdays) is that the mountain is fairly empty. No lift lines, no crowds. The lift system is excellent, and it includes a gondola (seating 8) that gets you to the top and protects you from the cold. The ski-in/ski-out accomodations are nice, but must be reserved in advance (around October-November).
The base mountain is very quiet and night-life is non-existant (exactly the opposite of Tremblant), but they do have some nice restaurants. My preference is to buy the food and eat in the condo, around a nice, cosy fire-place. There is nothing more romantic than good food, good wine, a warm fireplace and a view of the mountain to die for. View of the mountain at night, you ask? Well, Saint-Anne has night skiing on 2000+ vertical (served by the gondola and a high speed quad). And crowds are unheard of at night.
How about the skiing? Sain-Anne is a cruising mountain with decent grooming. Nothing radical, except for several bump runs that are usually well tracked and rather hard on the body. The best runs are on the left side of the gondola, where you have some blacks and double blacks that are steep, consistent in pitch, with about 1000' vertical (again, nothing that a good skier cannot handle).
How about the snow? Well, this is the East, so powder is rare. When it does snow, it is usually heavier snow than out West.
To be honest with you, Saint-Anne is far better than many of the ski resorts that make the top lists in ski magazines, but it is not well known. There is one more bonus: 45 minutes north-east from Saint-Anne is Le Massif, a 2500' mountain known for great snow (occasionally lots of powder). This would be a great day trip if you want some variety in your vacation.
Hope this helped!