You´re right, it´s more like a cave tunnel, like "Moria" style or something. Or just a cave tunnel, but meh. We´ll see.

As for the freedom thing, I would love to be able to reach nearly every place that I can see. It would give a big depth and immersion to the experience. In Lake Hylia, if you followed the edge of the lake by foot, you could eventually find two gossip stones.

The developers were inspired to make a world that feeled bid and was interactive, but not as near as they´re inspired to achieve that in TP.

Edit:
I´ve noticed something quite interesting... Just watch the trailer in the scene were Link is riding the creature. When he almost reach the bridge (or little time before boosting), something happens in the two large pillars more far away.

I remember someone saying that the creature fires something out of it´s mouth. I never found any button saying this, but I noticed some explosion that appears in the creatures "mouth"... but I watched closely, and I found out that there was another explosion in the right pillar... the pillars were exploting!!! Just watch for yourself. I´m tired of taking conclusions, so I´ll stop here.