I was a huge fan of the show when I finally got around to watching it, even with the sort of dangerous way that they wrote it, I thought Mr. Moore and crew delivered an incredible experience.
"The Plan" was interesting, but I think it was un-necessary, if you watch the extras on the disk, I think it's the actress that plays Boomer that sums it up, in no uncertain terms:
Spoiler.....
"The plan was to kill all humans, if you thought there was anything else, you were just deluding yourself.", period. OK thanks for that.
The movie fleshed out some characters a little, it was kinda neat to see some backstory on Anders and the resistance group. It was nice to see effects shots of the other colonies, which I assume have been culled from upcoming Caprica materials. The actual attack on earth was cool to watch for the effects shots and the Basestars. I guess the way Boomer acted through the show makes a little more sense, although now I am curious about the significance of the elephant? weird....
As far as future Galactica movies, given that they are making the Caprical Prequel, and a great deal of the show is green-screen anyhow, I don't think they will have any trouble coming up with the effects they need to do so. I hope they can come up with some compelling stories though, because the framework that they had to work with for "The Plan" didn't really allow them to innovate much, or really do much with the characters other than explain their prior actions a little.