Markus - I can't speak for all those who had bad experiences with an iRig but I suspect the main problem was as a result of using the original model - the one that plugged into the headphone output.

The HD model of the iRig, or the Pro (which is what I use) have the lightning (or 30 pin) digital connection. This makes all the difference in the world. I'm very happy with my choice... that said, I'm sure there are several interfaces available that are better still. My choices were limited by my requirements. The unit had to be small and it had to have MIDI in. Good sound, too, of course.