I have been there about 4 times, and IMO it is a very underrated place.
Have been to Val Thorens, Tignes etc too, so can compare
Only downside to the "Grandes Rousses" area is that part of it is on slopes that are relatively low (for french standards).
The famous Sarenne slope starts at 3330 meter, is a whopping 16 (or 18) kilometers in length (yes, 10 miles) and has a height difference of 1800 metres. This is really one of the classic descents, starting on the glacier, wide-open, some steep parts, and ending by a path through the Sarenne gorge.
Downside (as said above) is that this descent is partly south-facing, and it ends at 1500 meters. When snow is bad, the second part of this run is closed. There is another run that goes partly parallel.
When snow is bad, both runs are closed, and you lose 25 kilometers of piste in 1 go!!!
This will normally not be a problem between mid-january and mid-march.
Apart from this, it is a very nice area, especially suitable for groups of mixed ability. The slopes directly above the village are easy, very wide (up to 200 metres). The area has one of the (maybe THE) biggest installations for artificial snow in europe, more than 1000 cannons.
The higher up you go, the steeper the slopes get. From 3330 (pic blanc) there's the tunnel-piste, which is one of the steepest slopes of europe. consistently steep, over 500 metres of height difference. When you fall, you don't stop...there are guys with binoculars sitting on the bottom to keep an eye...
The further away you go from the main lift-axis (alpe d'huez towards pic-blanc), the quieter it gets. That is also where you find the best carving terrain. But the main slopes are also very good, but more crowded. For instance, the red Chamois from 2700 to 2100;
For instance, on the other side of the Sarenne gorge, is the area of Auris-en-Oisans. this is a noth-facing wide slope, 600 metres of height-difference, wide, and the angle is almost constant over the whole length. and it is quiet, quiet. and the lift back up is a fast quad detachable.
Then there's the part above Vaujany. some nice NW facing runs, maybe 400 metres of height differences (so not extremely long) but again wide, good snow, and empty
new this year is the funifor marmottes-3, so now there's a second point where you get up to the glacier
Here is a short list of slopes you cannot afford to miss:
-Sarenne
-Combe Charbonniere
-Pic Blanc - Alpette - La Fare (Enversin d'Oz). 2200 metres of height difference...
For eating, be sure to go (at least once) to "Les Airelles". It's on the left side of the slope from Alpette to Montfrais, in the Vaujany part of the area. This is one of the best mountain restaurants I know of. It's authentic, not chiq, food is superb, and the people are nice. It's an old farm that is built against a rock wall. Actually, one of the 3 walls is...the rock wall!
http://www.skimaps.com/Alpe_d'Huez_skiarea708.html
You'll have a great time, Alpe d'Huez is fantastic.
By the way, if you get a good powder-dump, be aware that La Grave is only 90 minutes away by car...