I first bought one from Stentor (Conservatory) but it had some cosmetic issues like white glue inside the box being visible via f-holes while playing and the smell being quite off (really, not the usual wooden smell); in addition its tone was not as mellow as I hoped for, even with more advanced strings. So I returned it and decided to check Yamaha's. After a consultation with Thomann I was advised that this model was adequate to my needs and spending more money would not be necessarily useful in my case (a casual hobbyist playing at home only). Thanks Thomann!
I am absolutely happy with this viola: it sounds just as I expected even with the stock strings (actually changing the strings makes it less mellow) and I enjoy practicing last weeks, it seems to be sounding even better now. (And yes, the smell is totally nice here.)
Tip: use the supplied rosin with the stock strings if you are after mellow sound, "better" rosins that I have make them sound more powerful, which is not exactly what I want.
The viola is not 100% perfect cosmetically speaking, like purfling lines are a bit blurry in a few places (which means it's imitation perhaps?) but this is visible only if you are very closely inspecting it. Overall it looks very pretty!
Note that the actual color is less red than on the photo: it's more orange and less saturated, but this makes it even more pleasant! The layer of varnish is thinner than on Stentor instruments which makes it less glossy and that's something I like as well.