They changed the site around, so if you choose destinations, WDW, MGM, Entertainment/Shows, you will be able to view a short clip of it. I would never miss this show, and sometimes see it twice during a trip. To me, it is the best WDW theme park night time show (with no separate fee). We have done it with and without the dinner pkg, always choosing Hollywood & Vine. I would only do the dinner thing if I was going during a busy time. We've gone 1 hour early and gotten decent seats. The hour goes by quickly, although the seats are like metal school bleachers, so if you bring something soft, like a sweatjacket, you may want to sit on it. It is a good idea to grab some counter service food and bring it into the theatre to have a "picnic" dinner before the show. Or, skip lunch and have an early dinner with their Fantasmic dinner pkg. You could always have a snack later at your resort. One thing to be weary of- once the show is over, the whole theater literally pours out towards the exits of the park. It is very crowded as everyone is leaving at the same time. I would either leave a few moments before the end (after you see Mickey appear on the top of the mountian) or stick around a few moments until the theatre clears out a bit.
SPOILER*****
The show is an amazing combination of lazers, lights, fireworks, characters, and music, with actual scenes from Disney Animated features being projected onto sprays of water while scores of music is playing. It includes villians, Mickey, the Princes and Princesses, as well as a lit up boat scene with many of the characters on two levels waving at you as they round the lake. It is pretty loud and dark at times, so young children may be afraid.