DLCs are out, for US finally(rest of the world it was out last week). $12 buys you all the extra DLCs released this time, includes Spa, new Kart track(s), the aforementioned addon cars, new colors, and new racing gear.
Spa is great, AFAIK its the most recent version of the track uses in F1, using the F1 start-finish line. Only tried 1 new car so far. Is it worth $12? Considering thats like a fifth of the price of a full game, probably not. But GT5 is lacking content and I'll probably get whatever is coming out anyway, if it adds cars or tracks.