Catching Fire has a lot of new characters. If you saw The Hunger Games, you know that a lot of the characters were killed off and now they introduce a bunch of new characters in the sequel. Well, now we have the news that Phillip Seymour Hoffman has been confirmed to play gamemaker Plutarch Heavansbee. Plutarch is an important character in not only Catching Fire, but in Mockingjay as well. Lionsgate has confirmed Hoffman, but there is another actor that is reportedly joining the film that Lionsgate has not confirmed. Jena Malone (Sucker Punch, Hatfields & McCoys) will reportedly be playing Johanna Mason, a brutal District 7 tribute. Again, that has not been confirmed by Lionsgate, but it sounds like it will happen.
I like the idea of casting respected, Oscar-winning actors in some of the main roles. That technique seemed to work well in Harry Potter (almost every British actor on the planet) and I like that here as well. The only film I've actually seen Hoffman in is Mission: Impossible III but I know he's won Oscars and is a good actor. I'm less familiar with Malone, but she might work in the role.
I think that Hoffman is a good fit, but I'm less sure about Malone. I haven't seen anything, but I'll assume that she works in the role.