Honestly, just never used it (not since freshman year almost two decades ago). I mainly use eclipse and it works very well for me. I like how I can hover over a variable and it tells me info about that variable, click on it and it shows me very other place it is used. I can rename a function and it gets updated in all files where it is used. I can very quickly see where a class fits in the class hierarchy or see which methods call other methods.
Emacs might do all of this, but eclipse does this well enough.
Emacs might do all of this, but eclipse does this well enough.