The main advantage of staying here is the included therme admission, especially the 7-11 am guest exclusive hours. There are relatively few dining options in Vals, and you'll probably end up eating at the hotel. While the food is good expect to pay 50 CHF a person for dinner at their cheaper Chessi restaurant, if you plan on eating at the red restaurant, book the meal along with your hotel for a better price.
Breakfast is not extravagant, but everything that was included was fresh and quite good. There were a selection of local cheeses, crude ham, boil-it-yourself eggs, a good selection of breads, yoghurt, jams, and other standard breakfast bits.
The threme is, needless to say, great. There are pools of 14, 30 (32 in winter), 33, 35, and 42 degrees celsius. There is also a three level sauna, as well as a nude are, if that's your thing. We went during the morning before outside guests could go and it was quite empty.
If you stay at the hotel, your therme pass can still be used until to get into the therme until 12 noon even after checkout so in theory you could stay all afternoon at the therme.