I'm thinking about buying Burnout Paradise: The Ultimate Box on Steam. I also want the addons to the game, such as Big Surf Island and Cops and Robbers. Are they available for PC or only for consoles? Are there any addons available for PC?
The list of game-changing content released to Burnout Paradise is available at this wiki:
In that page, there is a table that shows what kind of content is not available on PC.
Also, the "Burnout Paradise: The Ultimate Box" includes the Bikes addon (and maybe one or two updates too), but it has a bug that won't let you change the colors of the extra unlocked bikes. This is a known bug and was fixed in Big Surf Island update. However, since Criterion Games won't bring that update to PC, we're stuck with that bug forever. :-(
I'd add a link to the actual bug report, but Criterion Games Bugzilla has changed the address and now requires login.
Although the console version has more updates and more content, the PC version is still good. On the other hand, given the choice, it's probably better to pick the console version.