Having waited for a long while for my 4 oscillators and also having read the previous review, I found that my oscillators track well, maybe they've fixed the problem. There is a preset on the back which allows the user to fine tune the tracking .
The overall build quality is excellent especially considering the price. The controls have a feel of quality even if, behind the panel, they are tiny.
Sound: I used one of the original ARP 2500 systems in the 1970s and I knew what I wanted to hear. These small, cheap oscillators deliver. By using them with the other modules in the range you can hear some of the characteristics of the original 2500 in general and I am happy with that. The only thing missing is some of the noise which came from all those matrix switches but unless you are wanting it, it's no problem.
Summing up: Great value. Authentic sound. Reasonably authentic handling. Did I mention great value?