I should really give this a few more days, but I can't get over how few reviews there are on this so I feel duty bound to let you know that this is a top quality interface.
Build quality.
This is a cliche at this stage, but this IS built like a tank. The knobs and buttons are better than those on the ID22, I own that too. There's nothing loose or flimsy. It's a solid build.
Bah humbug.
Maybe it's just me, but every interface I've ever owned would hum when I plugged a guitar or bass into it. No hum with this, which I wasn't expecting and I've used lots of interfaces over the years. They do mention "de-coupling" and stuff about clean power etc, so it obviously counters the hum.
Sound quality.
It sounds great, big and clean. I've had the Apogee Duet in the past, this sounds better to me. They did say that they reckon it sounds better than interfaces in the $2k range, I wouldn't know if they've achieved this as that's out of my comfort zone, but you won't be disappointed.
Features.
This doesn't make your bed or walk your dog. There's no built in plugins or guitar sims. You can't record your 32 piece orchestra with it.
it's a straight forward 2 in 2 out high quality interface.
Headphone out.
I use Sennheiser HD600 and they sound great with the 2x2. Again the sound quality is excellent.
In conclusion.
This is pretty much perfect for my needs so I can't really fault it. The only unknown is, how long will it last? I'm assuming it will well and truly outlive its 3 year warranty period based on the build quality and the fact that it's not trying to do a million and one different tasks.