Was he successful (depending on how you define "success")? Yes. Did he impact the world enormously? Yes.
However celebrating him simply because of these is just plain stupidity. He was a murderous, incredibly greedy asshole even by the standards of that time. He did not prove that Earth was round, anybody knowledgeable of history knows that. The ancient Greeks proved that Earth was round (Eratosthenes - Wikipedia, the free encyclopedia) and Eratosthenes' method is widely known and taught in basic geometry. Anybody could see that the way the shape of the view of the moon changed, and the fact that there was always a round horizon, and conclude that the Earth was round. The knowledge that Earth was round has been around for several centuries before Columbus.
It is also ridiculous to excuse his flaws because he impacted the world or had positive qualities. That is akin to celebrating Stalin because he also undeniably impacted the world in which we live in and was a great politician who was excellent in maintaining power. Columbus should rightfully be remembered and be in textbooks but to celebrate him is being just ignorant of commonsense history.