Very well done! This is the most unabashed Fan-Service film I've seen since Serenity...and I daresay, it caters to its fans even more than Serenity did.
In fact, my biggest complaint about this movie is that it might cater too much to fans, leaving newcomers in the dark. The movie re- introduces you to Veronica, but virtually everyone else gets no exposition and no character development (beyond what you'd see in a typical episode, that is).
For fans of the show, this movie is a gift. You basically get a new episode of the TV show here- a bottle episode that's roughly 100 minutes long.
There were a few differences- namely, I didn't remember the show being this funny. Veronica always had a good sense of humor, as did her dad, but in this movie there were a surprising amount of laughs.
Also, the mystery isn't as deep as the full season one and two story lines (obviously). What's worse, I don't think the resolution of the mystery has that same "I should have seen it all along!" genius that made seasons 1 and 2 so special. I'd say the plot is comparable to one of the mini-arcs from season 3.
Lastly, as good as this movie is, it still doesn't exceed (or even meet) what the show already did at the top of its game. The emotional highs and lows are the same old thing as before, and the plot isn't nearly as neatly connected. I'd say I rate the movie as slightly above season 3, but not as good as seasons 1 or 2.
But what the Hell, you get to see Veronica work again, and it's too much fun to pass up!
Fans must see this movie.