We ate there a couple of weeks ago. We hadn't been in over a year.
You have to check in at a special desk set up on the second floor of the Contemporary. From there, a guy will take you up a separate elevator just for the California Grill.
The view is wonderful, but the restaurant is kind of loud. The sushi chef at California Grill is one of the top THREE Sushi chefs in the country! DH had her sushi and said it was amazing! We tried a cheese sampler.... different cheeses (none I could pronounce) were paired with things such as a honeycomb, a fig cake, and apple chutney. It was good, and a neat thing to try.
The night we went, the fireworks were at 10pm. They told us when we checked in at 7:00 that if we were finished eating and wanted to leave for a while, we just had to show our receipt to the elevator guy, and he'd let us up to the observation deck for the fireworks. (We didn't).
Yes, the music is piped in on the deck, too!