I have both and have used them for recordingbon IPad for soundcloud and youtube.
Firstly, I have to say that the iXZ is very good value and does what it claims. If you need to use a condenser mic with 48 Volt phantom power than this is your best choice. Because it plugs into the combined headphone/mic jack of the IPad it is not digital quality recording, but it is very good.
There is no doubt that the Apogee Jam is far superior when it comes to guitar recording, Digital quality and absolutely clean, but the fact that it does not have phantom power is a big draw back when you need to lay down good quality vocals..
Bottom line, if are looking to record guitar and good quality vocals the iXZ is a very cost effective solution. if you don´t need phantom power spend a little more and get the Apogee Jam.