I mainly use this pedal for boosting leads on high gain British style amps/channels. And with the correct gain structure it does this just as good or better than any other pedal.
You can go from a subtle boost that cuts through the mix, to an over the top Zakk Wylde style lead tone, just by adjusting the relative volume and gain on the pedal and amp.
Running it into a clean amp, you can get some light overdrive and decent crunch tones. But for me, this pedal really shines when used into an high gain amp.
Being a BOSS pedal, and one of the cheapest ones, its no surprise that it has some low end roll-off. But this is actually favorable when using it to push a high gain amp, since the low end loss makes more room for the high-mids and treble which is needed to cut through the band mix, when doing solo/lead work.
The gain stage will also add bit of noise depending on the preamp gain and power supply used. So my recommended pedal settings for use with high gain amps are:
High volume and low gain, with eq to taste.
For low gain amps you can add more drive and pull back on the volume to achieve the desired tone.