The Wasteland isn't actually all that huge, at least it feels smaller than Oblivion/Morrowind because there's a lot less variation in terrain and feel, but it's still huge in the sense that there is a shit load of stuff to explore and discover, and getting around without fast travel definitely takes awhile. I bet you could cross the map in like 15 minutes tho if you could just walk straight without hitting anything.
WHY SO SERIOUS HAHAHAHHAHAAHAHAHAHAHAHHAHAHAHHAHAHAHAHAHAHAHAHHAA