The good:
- Open world
- The "ubisoft forumula" is working and getting even better (how missions, collectables etc. work)
- Nice gameplay variety (amount of guns, cars, boats and aircraft)
- Decent mission design of some missions
- Far Cry Arcade
- (Humor) This one in brackets as it is very subjective

The negative:
- Repetative
- Many "standard" missions (seek'n'destroy, loot x, go there etc.)
- Main Story has an interesting basis but ♥♥♥♥♥ up the delivery
- Some very annoing parts are not skipable (long winding intro, drug dreams etc)
- Random Intermissions (from story progression) that completly break any immersion and are just annoing - and can happen while you are doing something entirely else....
- Boring Character Design (yes, Vaas was great but trying to top him in EVERY GAME is just not working....)
- Minor Bugs (despawning lootables etc, more annoing than game breaking)

The points I can't judge:
- I never played Coop so I have no idea how that would work
- I hate flying/racing games so I have no real comparison for the mechanics of the vehicles, although i found em easy to control, which was nice for me :)

Tl;DR:
Buy it if you can't get enouh of the open world "ubisoft" formula and can cope with a bad story design, boring characters and really annong random story encounters. (i.e. if you love every far cry/assassins creed)

Don't buy it if ANY of that is going to flip you off,as you will have too much of that all the time and the open world gameplay simply doesn't make up for that!