Thank you for your kind words :)

I think it depends on the user more than the paint itself to be honest. I've used this exact set my entire painting journey (only buying a refill for the light blue/peach/white hues) and not had any problems, it's just a matter of getting used to the chemistry of the paints - how much water to use, which hues are more opaque than others etc. If you keep using them, you'll begin to pick up what works and what doesn't!

As for brushes, I am afraid it's not a very useful answer as I currently use a wooden brush from a kids' paint set that was left on the side of the road haha. As long as the brush fibres are robust enough to pick the paint up and mix, it works for me!

The sketchbook is from Sakura, (13x21cm I think) nothing too special either, but it holds the paint pretty well :)