I really never understood that one.
I played it for 5 seconds and there was so much interface and crap that I quit. Also, almost everything required premium. *cough*Habbo*cough*
I bought a lifetime Minecraft account for 20 Euros and I am content with it. And it is currently my most played game. Sure, Roblox sounds like good creativity, but at A FREAKING WII U'S PRICE (Lifetime Outrageous), no thanks.