I've played on an original Xbox before, and I too was surprised at the size of it.
When I saw the trailer/ advertisement for GooH, Far Cry 3: Blood dragon popped into my head, but it's worse it seems.
It is, yeah.
The city is new, but half the size of Steelport.
All civilian NPCs are replaced with husks, who all have an identical skin, so there's basically no design for npcs.
Combat/Gameplay is identical to SR4, with a little variation on the elements of your abilities.
There are no radios.
Fewer vehicles.
No cheats.
No character customisation.
Kinzie is thrown in as a playable character, but seemingly just to satiate the desire for a female protagonist as The Boss can be.
And then the quests/dialogue just seems awkwardly clunky.
I don't know if they have plans for a Saints Row 5 (I wouldn't be surprised, even if they've basically written any logical/meaningful plot progression out of the game), but they will really have to step up their game. SR4 was kind of alright, but a bit worse than SR3, and GooH is just lazy development.