in my opinion, a very bad design, it has to be put quite far from the wall because of the tilted necks and it obviously gets even worse with longer scale instruments making it completly useless for me, such an enormous waste of space! Don't get fooled by the specified dimensions...
Stability is fine but far from perfect since the instrument's bodies are not locked in but just sit on foam so it depends on the weight of each of them and they can collide on the side if you are not careful.
Build quality is also fine, it felt solid but nothing special.
A big disappointment overall for the price.
I returned it immediatly to replace it by a K&M which is superior in every aspect, no waste of space, better build quality and better stability, not close.