My opinion on this is a bit mixed. I love the dessert party and the parade viewing is a real bonus for me, but it does take up a pretty good chunk of time (about 2.5 hours total). Now of course you have the parade and fireworks themselves in that time, that presumably you would do anyway and likely with more time sitting and waiting for your parade spot. So, I calculate it more as just a little over an hour of "extra" time for the dessert party itself that some may view as wasted time.
Personally, I book 2
MNSSHP nights and use one of them for the dessert party with parade viewing and save the other one for trick or treating and characters and that way I don't feel rushed and I'm easily able to see and do everything I want. When I did just one MNSSHP with the dessert/parade viewing, I did find that I was a bit more rushed to fit everything in.