With the Jackal-hunting storyline, game world, collectibles, HUD, and downloadable content being the same between the two platform editions, the last key difference is in custom map creation. While the tools available are essentially the same, manipulating the design is a bit easier with a mouse, but control preferences aside, the console version places a size limit on maps, something the PC iteration doesn't do. This is most likely due to open and expandable PC configurations compared to the closed configs with known limitations of consoles, though the official line is that it's for "quick and easy downloading"; however, since every modern console requires broadband anyway, I don't see how this is a factor. If you really want the ability to make bigger, more detailed custom multiplayer maps, PC seems to be the way to go. Beyond that, multiplayer invites and matchmaking might be a little simpler on PS3, but otherwise offers basically the same class-based adversarial gameplay, with an optional DLC pack.
In the End...
Both offer an expansive, controversial storyline (though it does wander quite a bit; your gallivanting immediately and often has more to do with the locals than the Jackal), and while it doesn't offer the polish, depth, or playability options of titles like S.T.A.L.K.E.R., Crysis, or Fallout 3, for basic open-world, go-anywhere action with tacked-on class-based multiplayer, it's not bad at the current asking price of $20 on either system. If your PC is worth more than your car, go for the PC version. If you don't want to have to constantly tweak settings or mind having an entirely predetermined control scheme, go console. Personally, I have to give the edge to the PC version, given its available tweaks, save-anywhere setup, and mouse aiming. Your mileage may vary.