I came across Prince of Tennis in 2007 when my interest in manga/anime was still fairly new. It was my first sports manga and quite different from other mangas...in a superficial sense. Prince of Tennis, at least in the beginning, was the story of an underestimated rookie who had an ego as big as his rivals, and defeated them through evolving strategies. But it's also about a colorful team with different abilities, yet all sharing the goal of victory... maybe that sounds too idealistic.
Many of the characters have these defining traits ranging from Ryoma's arrogance, Tezuka's commitment, Fuji's thrill, Atobe's cocky facade, and etc. While a fairly realistic story at first, Prince of Tennis became a stereotypical fantasy story with reality-defying techniques. Yet deep down, they managed to stay true to the spirit of the story.
My main criticism stems from author favoritism however. Despite liking Seigaku, I admit that the lack of losses made them a somewhat predictable team, especially after reading Slam Dunk. While Hyotei and Rikkaidai are interesting teams, Fudomine has been a staunch rival of Seigaku from the beginning of the manga, and yet only about three characters on that team get any development. Some themes were often warped, as while on-court violence is discouraged, nobody seems to care anyway.
Prince of Tennis remains one of my favorite mangas/animes, even with the reality-defying techniques. In fact, maybe the techniques made the manga more interesting. After all, why read a sports manga if you could watch the actual sport?