I started using it when I realised that the beautiful tones I got from my guitars, amps and pedals at home had a tendency to get drowned when playing with my band.
I chose this equalizer after reading opinions on forums. I was looking for a affordable, simple yet effective equalizer, with a good build quality.
The GE-7 proved really effective at the task. Basically I use it only to make my tone sit nicely in the mix on rehearsals or gigs. I don't use it at home, because what I'm trying to do is to sound as good as home in a band context. I don't use it to create special sounds or to make my amp sound like another one, though it can certainly do that.
I would strongly recommend this unit to any guitarist playing in a band, especially if there are other midrange focused instruments. What works for me is : cut off 100HZ, slightly cut 200HZ, slightly boost 400HZ, slightly cut 800HZ, slightly boost 1KHZ, 3.2KHZ at unity or slightly below, 6,4HZ is basically the presence, so I adjust it depending on the amp and the context.
Building quality is what you expect from Boss.
Worth mentionning I didn't notice any coloration from the buffered bypass when the pedal is off.