Rested experience is working as intended right now as far as I can tell. So long as you log off or afk in a rest area (little moon symbol beneath the exp bar) you'll earn rested experience. It's designated by a darker shade of orange along the bar, or turns blue if it carries on to the next level. Also, it seems that it's percentage based, so if you'll earn an extra 50% of your level from rested experience as, we'll say a level 25 marauder, then you switch to a level 1 arcanist, that rested experience will only last for an extra 50% of that arcanist's level, and not the amount it would have for the marauder. This makes it more beneficial to use on higher level classes.