As a new Xbox One version player, I have only about 13 hours under my belt. There are a few things that jump right off the bat that would be nice if implemented:
Detail more clearly the different characteristics of each vehicle from in-game, so I don't need to go hunting through forums and websites to know the difference between each truck.
Add something else to on each map. I have carried logs, cleared watchpoints, and found locked vehicles. Add more tasks to do, like finding secret spots, secret items, etc.
Add some sort of NPC interactions, like traffic, quests, etc.
The best part of the game for me is the back roads exploration, so if I could complete a few tasks in the meantime, it would be even better.