I love Fantasmic and always make a point of watching it from beginning to end when at the Disneyland Resort.
However, the reason Fantasmic is great at Disneyland, and sucks in Orlando at WDW, is because Disneyland's version takes advantage of the natural setting for the show, as well as the use of the Columbia for the Peter Pan segment, and nothing beats the magical feeling when the Mark Twain suddenly appears at the end with all the characters on it.
The poster above who mentions that the original Fantasmic in Disneyland has an intimacy and charm that Orlando's version utterly lacks is also right on the money.
It's hard to imagine how that enormous harbor in front of Mount Prometheus is going to provide a good setting for Fantasmic. I don't think much of BraviSEAmo--who wants to see a lover's spat between fire and water ending with a cosmic schtup--but at least it's something on the kind of grand scale that is needed to fill the harbor.
I guess we'll all find out! And it's going to serve exactly the same purpose that World of Color will at California Adventure, which is to keep people in the park after dark so Disneyland (and Tokyo Disneyland) don't get so hugely overcrowded.