Powder is great, terrain is quite varied, Honeycomb Canyon
Nothing is negative here for my tastes
I've been skiing in Utah since I was a kid. I've always gone to Alta, Snowbird, or Brighton growing up, mainly because that was the places my friends wanted to go. I hadn't really ever tried Solitude until the last two years. Man, I've been missing out. I love this place. I've had some of the most amazing powder experiences there skiing in Honeycomb Canyon. It's such a great resort because you get all the same snow that Alta gets, though the crowds are nearly non-existant quite abit of the time. Even if Solitude's parking lot is full, you can find tonz of terrain that are empty as most skiers will stick to Moonbeam and Link lifts. Solitude also has some of the funnest terrain. They've got 6 or 7 green runs, alot of blues and alot of blacks. Alot of their blue runs are steep though and could be easily classified as blacks. Though if you are teaching new kids to ski, they've got great runs for that as well. Quite varied terrain.
The Solitude European Village is really quite a charming place to stay. It is a pedestrian only village that I let my kids loose in. They always find something to do, whether it's tunneling through the 8 foot snow pack, or finding new kid friends to snowball fight with etc... We stayed at the Powderhorn Lodge and loved it. It's about a 200 yard walk to the ski lift from the Lodge. They have a nice resort club there as well which has a ton of things for kids and adults to do. (Pools, pool table, fuzzball, video games, sauna, hot tub, )
I guess the only things I could really point out as negatives (which I think are positives) is the nightlife options are very limited with just one late night bar in the village. But with a family that's not interested in that stuff I think of it as a bonus. The only other thing I've noticed is their power seems to have gone out alot in the 2010/2011 season, which has been a bit of a pain. Other than that, Solitude is the place to go.