This post suggests co-op mode has some serious issues that render the second player into a sub-important sidekick and involves some inconsistencies: The example in that post mentions the lack of a second set of Dweller clothings in the beginning which turns the "blend in" motivation absurd*. So are the issues mentioned (and possible other ones) bad enough to recommend not play co-op at all, or at least not during the start?
Since this sounds probably too subjective, let me rephrase the question:
For two persons who have not played Fable 3 before, what restrictions of co-op mode should one be aware of, and which of them can be mitigated by temporarily playing solo?
*)I don't know the details, since I haven't started playing yet due to this question
Best Answer
I think it depends on the amount of realism that you want to achieve, and what type of partnership (just for kicks, business, or marriage) you want to enter into with the other person (and in the game).
If you want realism, then it helps if the second player has previously played the game - at least enough to get whatever item of clothing helps with the realism.
If you're married to your co-op partner and you want to marry someone in the game (to follow whatever story line you're interested in), then they'll get mad and want a divorce if you bring around your spouse (which in my case was my real spouse. That got weird).
From a business perspective it's important to note (at least as far as I've been able to tell) that if you purchase a property when the other player is out of the game, you'll have to sell, and re-buy it when they get in game if you are to share the property.
Another issue when screen sharing is that aiming gets weird. This is really important when you're on the Gnome quest. You'll have a lot greater challenge finding them with two people.
Other than that, I think you can accomplish every other aspect of the game when you have two people (even if they seem like a 3rd wheel at times ;)