I'm playing and yes it's quite a bit like Fallout 3. Dungeons lock to your level.
SPOILER-FREE STORY:
Today I was exploring a - beautifully designed I might add - dungeon full of supergobbos and past the first room I didn't stand a chance.
I did find a very nice bow and sword though, upgraded from what I already had!
I tried a couple times and died every time so I decided to leave and try another quest. 2 levels later I returned to the same dungeon and the ubergobbos past the first room were still challenging but manageable, and it feels incredibly rewarding.
Have fun on Friday!

EDIT: Maybe slightly more on actual topic: YES, GO EXPLORE! It's way cooler than it was in Oblivion because there's less structure or predictability to Skyrim's map and landscape.