Whether you're a boxing fan or not, the sharp writing, lovable characters, and inspirational nature of this Anime will definitely be able to hold your attention. The OST is composed brilliantly and fits perfectly with a boxing atmosphere. The pacing of the Anime definitely breaks any monotony it may build up as the passage of time leads to the characters having improved so much they almost box entirely differently. The back stories are well written and hard to forget, even the filler which is extremely rare feels like a treat to watch as you wait to uncover the back story of a character you've known for quite awhile.
Ippo's story of his struggle to overcome the challenges he faces by sheer effort and willpower will inspire you, and the twists and well placed cliffhangers will keep you wanting to watch more by the end of each episode.
I strongly recommend Hajime no Ippo (Fighting Spirits in the US) to anyone of nearly any age.