It seems like the people who are disappointed the most are those who hoped do a lot of rides during the party. I went during the first party, which was sold out, and it didn't feel like wall-to-wall crowds to me. If you want to do things which are unique to the party, the M&Gs are the things with the longest lines and you aren't really interested in those anyway.
If you want to do party food, Starbucks has 3 party desserts - but remember that Starbucks tends to be slow because people order fancy coffee drinks, it has no place to sit, and it has no takeout containers. I'm not saying to stay away, I'm just saying that it's nice to know this before you go in so you aren't surprised and frustrated.
I loved watching the fireworks by standing near the rail above the water, across from the Frontierland Shootin Gallery. I wandered over as the fireworks started. There was nobody in front of me, nobody next to me. A lot of people don't like this spot because they like to look at the castle during the fireworks. I found that except for the finale, the fireworks were going off over the water so this spot worked great for me.
I did several magic shots with no line, and I got a photo with the gravediggers with no line. I met Cinderella and Elena with no line.
I think you need to look at Page 1, decide what your priorities would be if you attended, and get input about those specific things. Make the decision based on your particular group's personalities. I don't believe in making a decision (any kind of decision, actually) based on "people say..."