Everything is great - up until Pandaria.
THEN IT"S SLOW AND LINEAR AND OH GOD MY EYES
Too much beauty, your eyes couldn't cope! Its okay though, you'll recover.
On topic though. BC leveling is a total bore (though I do like Zangamarsh just because it looks so awesome), I enjoy WotLK though, lots of fun there (Except for Borean I love all the zones!). Then once I hit Cata stuff I sort of go into a daze and blank its existence from my mind completely once I'm done.