I'm a 28 year old Indian guy living in The Hague. When I started my saxophone class with Jeroen, I had a very beginner level knowledge about it although I previously had couple of online classes for past 2 years. I had attended just 10 classes with Jeroen so far but the knowledge and the ability to play the saxophone I have gained so far is really impressive and amazing. I could notice huge difference in my playing skills and my confidence level. He is very humble & highly organized! There are lots of nuances when it comes to music and he made sure all the time that I understood and play them corectly! I'm sure that I'm gonna play like a "Pro" soon. 
Bala Indhiran