The Brazil star said he was apprehensive about meeting his Barcelona teammate when he first arrived at Camp Nou but now has nothing negative to say about him.
The Brazil striker had a reasonably successful first season in Spain after arriving from Santos in May 2013, scoring 15 times in 41 games for the Catalans, though his side finished the campaign without a trophy.
Speaking in an interview ahead of the World Cup, Neymar was keen to pay tribute to Messi's good nature, which he insisted disproved some of the damaging stories he had been told about the Blaugrana star.
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"Messi has surprised me in all areas," the 22-year-old was quoted as saying by Mundo Deportivo. "Before coming here, I had heard horrible things about him — like that he was extremely reserved and never spoke to anyone. Now I see things differently.
"In addition to being a genius, he was very helpful with me off the field. When I see how he behaves with people, I realize how much of a good person he is. I have nothing negative to say about him."
Barcelona ended the season on a disappointing note as Champions League semifinalist and runner-up in both La Liga and the Copa Del Rey, but Neymar nevertheless believes he has experienced a lot of positives, particularly with his development, in his first year in Europe.
"It was not perfect but it was not bad," he added. "It was the first time I'd lived outside my country. I missed my family and my friends. It was difficult at first, but I learned a lot, both professionally and personally.
"I learned from every player and tried to adapt my style to the team. Some are good on the pitch, others behave very well in training. I am incorporating the qualities of each one of them."