100% free. After playing for about 2 weeks I went out and bought the physical copy of the game and felt it was well worth it but there's definitely no trap involved. You'll see a bunch of people riding mounts around in the starting area, thats from elite or founders (founders = buying the hardcopy), but you get a mount once you get to level 11 normally. Other benefits are like having more character slots or lower fees on the AH etc... still can experience all the content in the game for free.
Well worth checking out if only just to get a feel for the combat