We went in 2013 and absolutely LOVED it!! So much so that we bought tickets to go to 3 parties during our early December trip last year.
It was not the same as our 2013 trip. They let WAY more people in now (or more people are going) There are now long lines for the free treats. The lines went fairly quickly, but we didn't enjoy going from line to line to line for snacks. A couple snacks we never tried because the lines were insane. I'm saying this from one of our dates that was on a "recommended slow night"
We booked 3 parties so we could focus on the unique Christmas offerings (parade, fireworks, dance parties, etc) the first two nights and rides and meet and greets on the third party. The rides were no longer worth it and we had far better waits at MK in the day with refreshing fastpasses (sometimes without). We waited 45 minutes for Peter Pan, which wasn't bad, but took up so much party time (especially if you're only going to one party) Rides also broke down, especially Splash and BTMR. Walking around, getting anywhere was insane and packed, especially before and during the parades.
All that aside, we still enjoyed the parade, fireworks and just being in the Christmas atmosphere. They choose our daughters to dance and play with cast members while waiting on the curb for the parade. It was a magical moment to watch them while the music was playing on mainstreet, the projectors on the buildings going and the "snoap" falling.
There were Photopass people everywhere, even in front of Space. It's always a favorite of ours to ride People Mover and see all the magical decor.
With all that said, we won't be going to MVMCP on our next December trip because the crowds killed so much of the magic. We handle crowds fine, but to experience the park that packed (trying to walk without bumping into someone) was too much. We are "make the best of it people", and still enjoyed the parties as much as possible. Maybe we'll go again someday if the experiences change, but we've decided to put our money towards more dessert parties and other offerings. We absolutely loved the Wishes, Star Wars and Frozen parties. The monetary value for the food is nil, but was worth it for the experience (even a crowded Plaza garden viewing, because there's still some sort of cap on people allowed) We expected this going into MVMCP (money towards the experience), but it just fell short.
My advice for going in to the party is stay late!! The last 45 minutes were much better (expect for packed shops) A lot of shows run late! The edges of the park are much less crowded and was able to do a little SotMK late on the last night. Also, have someone save a spot for character meet and greets early. Lines are very long and you will get warnings that you may not be able to meet a character while joining the line if it's too close to closing (I'm talking 2hrs + before) Don't worry about the free snacks!! Their monetary value is incredibly low! It's worth it to pay a few bucks for the unique party only snacks. Focus on the party experiences over rides.
If you are super Christmas people, then go at least once to experience it. If you can only afford a single extra experience and average on Christmasy stuff, look at other Disney offerings. You could do a dessert party, Fireworks cruise, a signature dinner, Candlelight Processional, After hours or EMM, just to name a few. No matter what, you're at Disney. You're going to find something you enjoy
Have fun!