Is it worth buying for the co-op mode?

[パンダ（Φ ᆺ Φ）]

I've read that the single player and co-op mode is in a separate map so I was wondering if they make the co-op somewhat lite compared to the single player mode, is it the case?

is there quests in the co-op mode or players are to decide what to do with no real objective?

[Daedrac]

There is a new map which supports solo and co-op mode (hot-join) and has all the same features either way.

[Pablo Croft]

The latest patch added some instability to the game (bugs, crashing) so join with caution. To add to what was said above, don't expect to raise a family with another player just yet. I hear there's talks about adding that, but it's just talk ATM.

[Morri]

The idea of the co-op is that you build and manage your settlement together with your co-op partners.
But only on the new map, which is about the same size as the old solo-only map. There are quests as well, but I haven't played through them yet so couldn't say yet how long the quest line is compared to the one on the old map.

Keep in mind that this game is firstly a settlement management game, and while it has quests and a lot of rpg elements; questing is not its first objective. That was the case on the old solo map as well.

As Pablo Croft indicated, atm you cannot marry your co-op players yet. But all players can marry an npc and start a family with that npc. Marrying co-op players will be added later on.

And yes, sadly there are some stability issues atm, mostly (but not limited to) in the co-op mode, which the devs are working hard on to fix.