Had a love hate relationship with it.
Still use it today and it makes music nicer. Do note that i feel the system has been tuned and tweaked for it to well seemlessly and well with the rest of the gear and room acoustics.
However nice additiin it is too me, i clearly remember that it also seems to boost the higher range by 2 to 3 db which i have solved years back by adding more attenuation to the tweeter and works exceedingly now, thats why i said it was tuned to fit in my system.
Otherwise, i.hated.it for that seemingly 3 db boost.in uppermids and highs caused pain to my ears back when i first added it.
It can work well in a darker system or if you play music and lower levels.
Just to add, it makes instrument pop more into the room with a wider staging, but with a drawback of also a less focussed center fill especially affecting voices making vocals less pin point and a tad larger than life.