I don't have
MNSSHP experience, but I went to the MHP last year for the first time, and enjoyed it. Would I do it again? Eh. But it was fun.
Treat-wise, I ended up with a small bag (if you think of a smallish gift bag with handles, this was about the size of treat bag) filled with name-brand candy, and some carrots and (I think) graham crackers and maybe apples. I went through like 4-5 treat trails with 3-4 candy drops on each trail. Off the top of my head, I remember Village Haus, Rivers of America (twice!), New Orleans Square, and the Lagoon; not sure if I did any others or not.
The parade was great. I'm not usually a big parade person, but I enjoyed it. Like someone else mentioned, it seemed "dark," but so much of Halloween does.... One caveat--I have sensitive ears, so I really didn't like the gravediggers, but I don't like the sound of metal on cement.
The general ambiance was awesome. Lights were lower than normal, fog was thick on Rivers of America, lots of costumes, and less people were all wonderful!
For the amount I paid ($72 last year, with a Visa discount, I believe), it was "worth it" but not worth it enough to do a repeat performance.... However, plenty of people go multiple times each year! It's just not something I work into my Disney budget. If I was taking a child with me that hadn't been, I wouldn't flinch at buying tickets again. As it was, I was a solo adult who enjoys Halloween, but isn't crazy-crazy about it.
It was nice to be let in 3 hours ahead of the party. I think that let me in at 3pm. I don't have an AP, so I slept in, had a late breakfast at Starbucks, rode the tram (haha, I love the tram, even when staying walking distance away!), people watched, and did some shopping before 3pm, which let me stay awake and ready for all evening in the parks seeing everything!
Kids missing 2 days of school for it wouldn't bother me at all. But then again, I have taken DD out of school for several days every other late-winter time to go to
Disneyland
Just don't expect a copy-cat event, and you'll love it!