My brother and I also enjoy the co-op...we did the same thing with the fishing for about 30 minutes on the first day we played it. I wish the campaign had been longer....FC4 campaign was SUPER long, same thing with FC2.
I also wish the co-op let you run the whole campaign together HOWEVER I do enjoy that you finally can do almost everything together and it count for both players. I wish the silo towers and items would count for each persons play-through rather then just the hosts....but that's okay too.
All in all - SUPER enjoyable game

just wish it didn't have a linear campaign that made you go through certain bits separately (or doing it over with yourself as host) such as silo tower destruction and specific campaign missions....but this also why I enjoyed the hell out of Forza Horizon 3 cuz I could play it with my bro and a friend of ours and just drive around and do ANYTHING and it count for all of us in our own individualized accounts (no linear campaign though so that is why it worked that way).
Definitely not disappointed I bought the game at all, 10/10 imho, just wish it had been a smig longer.