it just looks like an inexperienced attempt at photorealism. The artist did not capture any depth, or create any real definition with an actual lightsource.
I love the softness of the petals and the bright colors. It's beautiful and I don't think you should add any black outlines. Black outlines can sometimes look like a coloring book if they're not done well. It's unique and very pretty just the way it is!
Personally, I don't think it's as bad as the negative comments and insults would suggest. However, I do agree with previous comments about outlining the petals. That'll make it really pop. But I think it's already very pretty :)