It can have awesome properties sometimes but sometimes it can be terrible!
In it's raw form it's useless and extremely hard.
You can find it anywhere in the end, since it's hard you'll need a really good pickaxe in order to mine it, diamond or up!
Smelt it for Endium Ingots!
If you smelt it in an Ender Furnace you get two ingots instead of 1 ;)
If your end has already been generated but you want access to Raw Endium, you can turn on it's old recipe back (using the config file). It will be something like this: