Each installment of the Resistance franchise has arguably been monumental in the FPS world from R1: FoM being PS3's launch title along with R2's ridiculously great online.
Gone is Hale but Capelli returns along with Dr. Molokov. You can expect another blistering title with an engaging campaign filled with new and unique Chimera. The Chimera will be more intellingent than ever with flanking abilities and will periodically suprise the player. The weapon wheel is also back from Resistance Fall of Man days however, the online mode will be shortened down (no more 60 player TDM's) but have an even more polished feel.
There are 2 trailers out including one which has gameplay. I do recommend going on IGN.com and watching the 4 minute gameplay footage to see for yourself!
Expect this or Uncharted 3 to be named “Game of the Year”.