Never got into it, due to the art style being ass as you mentioned, but I can see the appeal when compared to other generic Shonen from what I've heard of it. Many of the battles rely on teamwork and tactics, making it more appealing than the typical slugfest and being what could be called "Power of Friendship Done Right". The cast of characters is also fairly colourful, even if not the most developed, plus it doesn't conform to as many stereotypical archetypes as most other run of the mill fighting Shonen it seems. It's locations also seem to stay constantly fresh and atmospheric.
From what I've heard, the anime is far more appealing. Although it suffers from a poor filler ending, the remainder of the manga's storyline is a drop worthy mediocrity anyway, so I guess going with the anime may be a better experience.
It's not like the series is one of the best Shonen, though. The villains all seem to be generic and as said before, it falls apart later on. From what I've gathered, it's overall not a terrible Shonen like Naruto or Bleach, but it'd be a stretch to place either incarnation of it much higher than slightly above average at best. It ought to be worth checking out if tired of a lot of other Shonenshit, though still less of a necessary experience to viewing some top tier Shonen, or top tier anime/manga in general.
