great runs, good variety of terrain
long lift lines, crowds, expensive
Disclaimer: I didn't stay at the resort village, so this review is just about the quality of the mountain.
Lift Lines: They're long. You can get there early and beat the lines. The Edge has considerably shorter waits. Also, the Expo Lift on the North Side tended to be a much shorter line. It's a pretty long ride down the mountain, so that somewhat offsets the long wait.
Crowds: Coming down the South Side at the end of the day is not an experience I'd like to repeat. The top of the mountain, especially coming off the Gondola and the TGV lift can be crazy crowded. The mountain is big enough though that you can avoid massive crowds most of the day, at least on the slopes.
Terrain: This is definitely Tremblant's redeeming quality. There's not much for beginners or lower level intermediate (though the green runs do go from top to bottom), but there are a great range of black diamonds for intermediate and advanced skiers. I loved the Reaction and Sensation glade runs on the Edge. Trees are spaced fairly wide and the slope isn't too steep, so it's especially great for people who are new to glades. Windigo and Fuddle Duddle were also great runs, though I don't think Fuddle Duddle is normally covered in moguls. Grand Prix was hands down my favorite run on the South Side.
Conditions: Our first day was sunny, around 25 degrees. By the midday, the tops and steeper parts of most of the runs were getting a little icy. The second day was around 35 degrees with DENSE fog clinging to the top 1/3 of the mountain all day long, but no ice. Overall, I was pleasantly surprised with the conditions. The ice wasn't anything more than normal for east coast skiing. Coverage was pretty good, but I think all the rain on Jan 1 and 2 wiped a lot of that out.
Maybe it was because my expectations were low from reading so many bad reviews, but I was pretty happy with the skiing to be had at Tremblant.