It will be stupidly simple to use. Just do:
$ craft create "My Instance"
==> Client or Server?
> server
==> Please specify Minecraft version:
> 1.8.1
==> Sponge, Forge, or Vanilla?
> Sponge
==> Resolving downloads...
==> Found download
==> Downloading Sponge 1.8.1 server
==> Sponge build 1012 downloaded
==> Downloading Forge 1.8.1 universal
==> Forge build 1234 downloaded
==> Creating instance layout
==> Copying files to instance
==> Instance "My Instance" created
$ craft start "My Instance" # This will run it in the background
==> Starting instance "My Instance"
==> Started
It also uses Gemfile-style modpack definitions. (You’ll be able to install it from that gist once it’s done)
$ craft clone 228510d619b73d7b5d69