There's not really much to say. It's a 4-way headphones amplifier and it works perfectly if you're recording or listening to mixes with up to four people.
As for the amplification, I'm not sure how well it actually works. I have a pair of 80 Ohm headphones and I'm not really sure if they are being driven better through the amplifier. If I had headphones with higher resistance, perhaps 250 Ohm, maybe the difference would be more noticeable when listening directly through my interface vs the amplifier.