I'm not a professional whistle player, I bought this whistle along with 3 others to learn and try them. And, of course, for fun :-)
This one is built well (it has only 2 pieces - a metal body and a plastic mouthpiece) and is quite stable in terms of the sound - It the plastic mouthpiece makes it quite reliable and predictable compared to whistles with wooden parts in the mouthpiece.
I like the sound and it's easy to use. I know other whistles that sound better to my ear but they also cost much more.
This one is very simple, but sometimes less is more :-)