From the las thread
I bet it may have the same freedom of mission choices than Mass Effect, and that as too much. But again, ME is also basically linear.
Deus Ex HR is also linear to some extend (you can't travel between cities at any time, it's not TES-style open world), but not in the way Mass Effect is. They may both be shooter/RPG games with a cover system, but they're not that much alike.
In Mass Effect you can choose to what level (planet) you want to go to, but then that level you go through is completely linear. Linear corridors with enemies standing still until you arrive to shoot at them. You can't jump or move any objects. The cities are slightly more open but there's usually just one way to get to your destination. If you do a mission, you'll go through the exact same corridors every time.
In Deus Ex you have a main story that brings you to a specific city hub, and then you can walk around everywhere there, doing side missions or main objectives or just exploring buildings, alleys and sewers. Completing the main objectives in an area results in the story taking you to another city. When doing a mission, there are all sorts of ways to reach your objective. That's the main selling point of the game, really. Multiple solutions to every problem and alternate routes to your destination. Some being easier than others depending on how you develop your character's augmentations.
So in Mass Effect, the choices you have are made through dialogue, usually at the end of a quest, which affect how the quest ends. In Deus Ex you have some of that too, but the choices you have are mostly in how you want to achieve your objective. Hack your way through a locked gate, or stack some boxes to get over it, or jump over it right away if you have the jumping augmentation, or use a fire escape to climb to the roof to enter the building there, etc.
That post turned out longer than I expected.