It's a great plugin. Fast and useful.
To make it perfect, it only needs triangle indicators instead of + and -. It's a little bit difficult to grasp where the indicators are. Maybe you could add a fast slide animation to make it easier for the eyes to follow where the content goes. Especially since the page jumps when I minify a block. I also think that there could a a more prominent indicator for hidden content (take a look at sublime text).