Micter,
I've used it occasionally just to see what it would do to a mix. I've only kept the result on one track so far - & it was reasonably well received in the mixing clinic. I used it very lightly and kept it on a piece that suited it.
If you have one handy or the plug in already installed don't be afraid to try it. Just don't expect anything. It certainly won't SAVE a problem recording or breath life into a dud but it is a tool just like exciters, reverb, delay, etc. If you play with it & learn what it does - like all your other gear - you might find a use for it occasionally. It's expensive though.
I've also used an aural exciter - I used to run a mix through it after then A - B the result. SOMETIMES it did something good.