When in November are you coming? Mystify ended at the end of the summer season. The last I heard, they do plan to run the show again for the busy times of the year when the park is open late (Thanksgiving, around Christmas/New Year's).
As far as whether it's worth staying for... it's a nice show, but it's not IllumiNations. By this I mean there are water walls with moving images, there is music, and there are fireworks, but it's not on the scale or the spectacle of IllumiNations. If you're expecting something that over-the-top, you'll be disappointed. That said, it's certainly worth seeing.
If you want a good spot to watch, you'll have to skip the evening Shamu show and find a spot. When that show lets out, everyone has to walk around the lake (the view from there seems like it would be really good, but it isn't), and they all crowd into the waterfront area.
