For game play I loved how they added and action camera and a cover system. I thought they were very nice touches. The story was all it was cracked up to be, The ending got me very sad haha. Except for a few glitches I thought the campaign was done very nicely.
What got me mad was the multiplayer. I don't know why Gearbox would hand it down to another company. I thought Road to Hill 30 and Earned in Blood's MP was amazing, It was so clever, but I never really got a chance to play with people online due to the fact I discovered it when it died down. Now I hear about this Furious 4 crap. I don't know what they are thinking.
Overall SP for me lived up to its expectations, I don't know if a few years was worth the wait now though xD