Difficulty wise..I'd say at best its a 6 out of 10
You'll spend more time on the million dollar trophy and 10,000 kills trophy than anything else..but I think for $1.50 I bought the botzone add on and finished those trophies quicker than most..instead of hoping to get a ton of kills playing against random people online..you can play against AI bots which are dumb as shit and it counts towards the trophies