The campaign was fun and definitely worth playing..but..for me not in the same league as the other Gears games. I guess that was expected to an extent. I know some prefer in game narrative to cutscenes but I think the lack of these compared to the main games took away some of the impact & weight of the storyline. Also felt a bit like an arcade game with a declassified mission (although I think these were a good addition) & stars for every section without too much variety. I prefer the distinction of a straight up cinematic campaign and a completely separate arcade mode campaign with scoring and everything else on.
I'm still enjoying Overrun and will play that till I reach the last achievement related rank. Otherwise once I've finished the Insane/Insane Declassified/Insane All Stars playthrough I might be done with the game (aside from DLC achievements). Will have been by far the least amount of time I've spent on a Gears game.