Minecraft has always taken a great deal of ribbing about the state of its graphics, which are simple at best. Some modders have decided to fix the shameful graphic issue by adding ‘HD’ texture packs in which the tiles no longer display at 16 x 16 per tile, but instead sit at 64x 64 or even 128 x 128 if people are pushing the limits of what can be done.
If you just want to know how to install HD textures, I’ve written a guide here. So go forth. The rest of this article is going to be dedicated to discussing the relative merits of HD textures vs the default 16 x 16 texture packs.