The Good: The skiing in the La Plagne area is very good. We've been to most of the major places in France, Switzerland, Austria and Scandinavia, and skiing wise La Plagne is among the very best. We stayed there in the very high season, and if you stayed up in the slopes (avoidng the few bottlenecks down below) there were very few ques all day.
The appartment we had was large, and had a nice view.
The Bad: The reception area is just a small room, the halls are dark and have a smell... Everything looks a bit rund down... Our appartment had a terrible smell, probably due to bad plumbing in the kitchen, so we had to leave water in the sink to try to trap the "gasses" from the sink... At first we seriously considered just leaving...
We had lot's of baths with jacuzzi bath-tubs, which should be pure luxury. But all the workmanship was terrible, so the baths looked cheap and unclean.
You pay extra to use the small pool.
The Ugly: La Plagne is not a high class resort, or a cosy resort. It's and industrial machine, built quickly and seemingly cheaply and with a minimum of attention to detail or workmanship. Most of the architecture is mid 60ies to 70ies French (or Soviet) appartment blocks.

If you're spending your hard-earned money on a skiing vacation to the alps: Go somewhere else!