ok first off the campaign, i haven't played it all the way through yet but it doesnt feel as good as the first game's. you don't really follow a set path around a character but you play episodes from different army's or watever. there's no connection with the characters whatsoever though. it's split into episodes each about 15mins in length with about 4-5 episodes in each chapter. the one annoying thing is that if you die you go back to the start of the chapter NOT the epidsode, which can make it tedious to have to keep replaying the same episodes over and over. Also, you aren't alone you can have up to 3 additional players on your team (either AI controlled or by people online) it does help to have other people fighting with you but the AI isn't that great and if you play with these characters you'll probably end up doing most of the work. The campaign gets 3 stars for me because although it can be frustrating it looks good and the bosses are pretty epic, but i'd recommend playing online rather than the AI.
On to the online play, i never really played the online from the 1st one but this one seems pretty good. It hasn't really pushed the boat out, just 3 match types available (deathmatch/team deathmatch/capture the flag) but the variation in each match is quite fun and unique. Numerous mech's/VS suits scattered around, shotguns, rocket launchers & also your grappling hook which is great for getting around the maps (which are pretty well designed) i'd give the online 4 stars as it's a nice change from all the fps' & the use of mech's/mobile armour suits/vs' makes it more fun to play.
Overall i'll give it 4 out of 5 it's a pretty good package but they should have done a more original and involving storyline like the first one and fleshed out the online but it's still fun to play. Also it's not a bad price for 30 quid