Everyone might already know this, but you basically get 728 extra slots to carry stuff. It makes it a little bit of a pain to get to what you want because you have to place the ender chest, pull out the shulker box, place the shulker box, retrieve the items you want, break the box, put it back in the ender chest, and then break the ender chest, but it's totally worth it. If every slot was filled with a full stack of blocks, that means you can carry almost 50,000 blocks with you wherever you go. I'm not sure if you can do it on survival on PC though because I don't think there's enough shulkers to kill, but in CE there's a "Resent the End" option, so that shulker shells can become totally renewable. Also a Silk Touch pickaxe is pretty much mandatory because you'll be breaking that ender chest a lot.