Technically, they're calling it a "teaser trailer". The footage in it only covers the first 1/3 of the book. A full theatrical trailer should be released later.
I haven't read the books yet, but I really enjoyed the first movie, so I'm looking forward to this one. The trailer was pretty great. I waited to see the first one on DVD, and kind of regretted it. I'll definitely be seeing this one in theaters. I plan on trying to read at least the first two books before this come out.
If you don't manage to read Catching Fire before the movie comes out, try to avoid online articles, or even IMDB summaries. They all spoil the big twist that comes halfway through. Lionsgate has so far tried to avoid spoiling it in their promos, but the media don't care about that.
I'm very happy with how this looks like and what they're focusing on. Philip Seymour Hoffman's role is expanded just as I expected it to be. One of the things I liked best about the first movie are the added scenes outside of Katniss' POV, explaining Snow's and Seneca's reasoning. Here they work really well since they explain Snow's motives better than the book does (in the book, we can only guess at what his real plans and motives are, since Katniss isn't aware of them herself). Suzanne Collins worked on the outline for the script with Francis Lawrence, just as she did with Gary Ross in the first movie, so there's no doubt that all the additions are approved by her (or maybe even her ideas).
Although maybe the villainous muhahaha was a bit too much.
Other than that, there seem to be only some slight deviations from the book, which I won't get into, but the most important scenes come straight from the book. The riot scenes look great. It seems that Francis Lawrence might have drawn some inspiration from the Arab Spring, Egypt specifically: