Hmm well I'll do an overall rating whilst I'm at it...
I've played a fair bit of Ghosts (prestige 3) so i'd say my opinions pretty good!
Okay first off campaign - Campaign was your usual, but it was great at the same time, unfortunately I get glued to military games easily anything military real life etc I love it so some may find the rest a bit bias but I'll try and keep it as unbiased as I can...
I felt like the campaign was good, I loved this whole 'Ghosts' thing - the mission where you scale down the side of the building really wowed me I loved it - The storyline wasn't that strong but stronger than others in my opinion, I very quickly got myself attached to the person you're playing and of course Riley. I love the way they left a greater power which we don't understand 100% yet keeps me interested at the least! The mixture of present and past missions was nice and the vehicle combat, controlling the loki etc was pretty solid. The big thing that I found distasteful was...no real stealth missions ... Chernobyl on CoD4 - That whole mission will forever remain one of the best moments of gaming in my opinion - Somewhat unrealistic with the shear amount of people there are but still..anyways ..yeah no real stealth missions :/ The whole 'Ghosts' title and trailer had me excited for some heavy stealth missions (well a lot) but alas no the jungle part where you're on your own was pretty fun but still meh. Overall I'd give the campaign about a 7/10 as it drew me in and I enjoyed every part of it. Again I'm a huge fan of singleplayer so others may find that rating odd! The ending is a huge cliffhanger which will make me (unfortunately) by the next ghosts.
I know this is only Singleplayer but heck, Multiplayer has kept me going, how quick you die and the new perk system really flows for me. I love it. Unlockable stuff for your character and that personalisation is another quirk I personally feel is quite nice. However multiplayer is let down by how quick you die as well. I find (not much but it's there) some lobbys the players are to afraid to get out run around and just blow each other up, which is what I like. Also on that note - The lag compensation and just a general feel of elastic banding can make me stop playing after 30 minutes but still Multiplayer gets a 8/10 for me
Extinction - I love it, something different yeah it doesn't suit cod but what the heck, blowing up aliens with buddy's and an actual goal to achieve is what I love. Zombies got boring for me very quick as there was never a ...YES WE F*ING DONE IT moment.. just a oh wave 29 cool.. Black Ops 2 was far better for zombies but still extinction tops it. Extinction only gets a 7/10 because it does get repetitive and it can be finished very quickly without relics...
Squads .... Hmm not a fan too much but again something nice for the casual gamers of cod, and offline players I'll give it 5/10 just purely because it adds something more for the before mentioned players.
Overall Ghosts - gets a 7.5/10 from me I'm still playing it and the mixture of clan players which can be really good at times and the new maps I personally feel IW done pretty well with. This CoD feels that bit more of a tactical shooter to me, nothing great so when I say tactical I use it lightly but when you meet a player with skill on this game it really shows!
I wouldn't say it's the worst cod that for me would be WaW then followed by Bo2, Bo, MW3, MW2 CoD4 still remains king for me, I'll top my hat to IW for staying in the game this long and still producing games that do great at what they play for.
As above mentioned a change in formula could perhaps ruin these games... but a new setting or perhaps something a little less similar might bring the CoD franchise back up. Still Ghosts done miles better for me than BF4, that game blew so much on PS4. BF3 is still my love <3