I choose this white forte double ocarina after I was impressed with many sound samples I heard of it. That it is made by reputable maker Focalink/Stein and affordable for a quality double ocarina was definitely also contributing factors.
It'r very beautiful and looks like a very professional instrument.
I believe this is the same model as the straw-fired double forte by the same makers, but I can hear a minor difference in sound between the two ocarinas. However, it is very slight, with the white forte sounding clearer and the straw-fired has a bit more texture.
The fingering chart that comes along gives clear instructions, followed with sheets for some songs to learn.
As it is a forte ocarina the sound is louder than other double models by the same maker (i.e. the Dolce double). It is clear, wonderfully bright and not airy even on the higher notes. I have been told that your breath pressure needs to be rather strong to play it, but personally I thought it wasn't that bad. The rising breath pressure is very even throughout the range. The highest notes on the second chamber are very loud, so I do not recommend playing them when there are animals with sensitive hearing around.
As for the ergonomics: obviously it weights more than an average single chamber alto, but according to my research it is still fairly light for a double chamber.
In the beginning I found it somewhat difficult to hold; with the placement of the two voicing holes in the back it took some experimentation to figure out where to place my right thumb.
The second chamber has a hole to the right of your right pinky finger that is meant to be kept open, and I imagine that for someone with bigger hands it might be too easy to accidentally cover it up.
Another ergonomic feature that I still struggle somewhat with is how closely placed the blow holes for the different chambers are. However, these are things that can be overcome with practice and getting to know the ocarina better.
In short:
Great, clear sound and evenly rising breath pressure.
BUT somewhat tricky ergonomics. However, this can be overcome with some practice.