Everyone has their own opinion about things. No matter how good you are, not everyone will praise your work, as THE perfect picture will always vary from person to person.

While Randuin's criticism might not have been as creative as it could have been *snicker*, you will still have to remember not everyone can like your work. Hell, if everyone praised your work, you'd never want to improve. I mean, why bother, when you could keep making very similar art and get applauses every single time?

Practice makes perfect, and the practice never ends no matter how good you are.

"Stephen Wolfram is the creator of Mathematica and is widely regarded as the most important innovator in scientific and technical computing today." - Stephen Wolfram