Wow, no reviews for four years, that seems incredible. Big change since the last reviews is the increase in snow cannons ensuring that the run down to Prarion from Tracouet is snowsure all season: and this year the new gondola from Prarion to Plan du Fou making the trip over to Siviez a doddle. There is also now a piste (black) from the top of Plan du Fou through the mogul field that was previously the only way back from Siviez. The gondola is continuous, so if you're tired after a long day you can get on it at Siviez and stay on to Prarion.
The main skiing attraction for me is the itineraries, which make for challenging but generally safe off-piste skiing unlike anywhere else I know of in Europe. Mont Gele, Gentianes, Chassoure, Mont Fort, Vallon D'arbi and l'Eteygeon should keep most experienced skiers happy for the duration. The pisteurs are generally very vigilant and do their best to keep these open, but if they're closed then stay away; have been in the resort when there have been fatalities on these routes when they've been closed.
Nendaz has been massively developed over the years that I've been going there; massively over-developed some would say! But this means that for anyone wanting to rent an apartment or a chalet for their holiday they are spoiled for choice. it also does mean that there are lots of new wine bars and restaurants opening up and again plenty of choice.
Big negative is the car parking at Siviez during peak weeks and it remains to be seen whether the new gondola/lift link between Nendaz and Siviez will ease this problem. Hope so as someone who often goes during school holidays. It's never put me off, but it would be a big plus if you could drive over to Siviez and be certain of being able to park within reasonable distance of the lifts. And they ought to be able to ensure that this car park is not a skating rink when the temperatures are low!
Overall though, a great place to go and as has been said before, a great way of accessing some of the best skiing in the world without paying Verbier prices!