The problem is that the 2i2 3rd gen ships in mass storage mode. So when you plug it into your computer the first time, it appears like a usb drive and is not usable as a soundcard. It needs to be set into its operational mode before you can actually use it, which is done using Focusrite's control software. But sadly the software is only available for windows and mac. So I had to go to my parents place, plug my scarlett into their old windows pc and download the necessary software from Focusrite, which then performed a firmware update on the device and set it into "sound card mode". After the firmware update the scarlett worked without further configuration on my Arch Linux laptop.
I don't know if there are other ways to set the device into operation mode, so if you don't have access to a windows or mac computer, I would advise against buying this audio interface.
Although, when you got it working, it seems to be a pretty good audio interface and i had no problems so far. Nice sound, very low background noise, good latencies, and I like the direct monitoring feature. I really don't need the 'Air' feature, but that might just be a matter of taste.