This game really makes Mass Effect 2 look bad (a game I thoroughly enjoyed). Every combat mission in ME2 was a narrow hallway, no options. Every hub felt small and load constrained. And worse, all the loyalty quests in that game were, "Hey Shepherd, I'm really tormented over this thing that's been haunting me for years. Can you help me?" "Sure. Wait, this only took 30 minutes? You're the most badass member of your species and you couldn't do this one thing without me? It took thirty freaking minutes on one planet. In one location. I only talked to one guy. None of this was hard or difficult or hidden! WTF!"
These sidequests feel beefier, more non-linear, etc. And while I'm not far enough into DX1 to compare to that, these levels offer so many different ways to move around and solve problems (for example, there are 4 ways into police station alone).
This game is a breath of fresh air.