I think six episodes in the first season was enough, we've seen lot of things, not understand everything and the season ended. More episodes would've been great (I don't want spoil so I don't say more) maybe to develop the characters or their relationships but I enjoyed S1 the way it was.
The serie is renewed for a second serie of 6 episodes and I prefer waiting to see it before saying if it's enough or not. Sometimes series just need 6 episodes to be amazing, I think it's the case of Utopia.