OP-Z : Amazing instrument! Lots of menu layers but highly intuitive.

When you first open it you worry it will be difficult to learn how to use this because of it being so menu-driven but the quick-start guide and overlays are so intuitive that you learn the interface within 20 minutes.

I've been using this to write music while on planes and trains and to demo out new ideas worked on in the rehearsal room too.

One small issue I've noticed (and read online along with the OP-1) is that in some situations you get a loud buzzing noise if the instrument is charging via USB on a computer/laptop that is also being used to record the OP-Z from the line-out. (Only if it is the same laptop/computer). This is because it is non-isolated and creates a ground loop. I've seen isolators that can fix this problem so should be OK (and if you don't have it plugged in to charge it is no problem). For this reason I haven't marked down the OP-Z in my star rating as it is a work-around-able issue.

Overall it is incredible. Certainly very expensive but you can tell a lot of that cost is for the large amount of time spent on research and development from Teenage Engineering.