We did MNSSHP for the first time last October and loved it! We did it two nights--Friday and Sunday. On Friday, we spent the night doing the special attractions such as the parade, headless horsemen (not to be missed!), etc. and spent just a small amount of time on the rides (though we got on quite a few--the lines were minimal). On Sunday, we did the opposite. We saw only those special things we truly enjoyed a 2nd time and spent the rest of the night on the rides! No more than a 5 min. wait on almost everything! It was great!
The ticket price is seperate from your park admission passes. I found it was cheaper to buy my MNSSHP and to spend that morning doing DD or the pool, etc. This way I did not use a "day's pass" and we still got into MK! We could get into the park around 4:00 and you have all night. We did PS at LTT around 5:15 and it worked out perfectly (do PS early!) We were finished shortly after the park started to close down and prepare for MNSSHP. Guests staying for MNSSHP were herded into Tomorrowland where most rides were running! This way we beat the crowds into the park that evening as well.
One thing I will say, we skipped most of the trick and treat stations. My DD is 16 and they were very busy. She can get the candy elsewhere and the bag got some of a nuisance to carry around all the time.
You get a free picture which they send to your home. Our first pix we did as a family and on the second night, we did "individual" pix. You just have to fill out seperate slips for each MNSSHP ticket with the person's name (not the same on each one). It was just my DD and I so she had her name on one and mine on the other. We then did a montage of all three pictures and framed it!
Hope this helps!