I mean, I undestand being dissapointed by it (I myself am), but I think it was pretty obvious from the beginning that, had they allowed us to wander around, it wouldn't be much, because of the sheer size and scale of the city (with all the citizens walking around) and plot reasons.
I always held some hope in regards to some of the narrow, flashy streets we saw in the 2011 trailer (which were a battle area, so maybe they're still in somehow), the Palace (this is a given, I'd say, at least some of it) and maybe its outskirts. But yeah.
Although, as much as I love Insomnia, at the end of the day it's another modern Tokyo-inspired city. I'd rather have cities like Altissia, Tenebrae, Treno, Lindblumb, Dollet, Lestallum...