The current state of 2D in Unity is currently a bit underdeveloped, due to the fact it was only recently released. After all, Unity is still primarily a 3D engine. One of the obvious things that are missing right now is the ability to have tiled sprites. As of version 4.5.4, you cannot do that out of the box without some nasty trickery. Current solutions you find online will usually have you replicate a sprite multiple times, but that’s far from the best solution; a Sprite is not just an image, it’s its own entity that comes with additional overhead.