Kenichi is a series that started well. However, due to the law of the hierarchy of bad guys, the anime does lose something towards the end that it had at the beginning.
Kenichi is a story of a bullied kid who goes to train under a bunch of crazy martial arts masters to become the strongest. His growing skills also earn the attention of the delinquents and local gangs determined to show that they are stronger or to beat him. At the beginning, you see him learning and using various techniques to beat different styles (i.e illegal moves to beat a club-fighter in a street-fight). It is done in a tongue in cheek style with the crazy masters and how they treat him providing much of the entertainment.
However, towards the end, the fights devolve into dragon-ball style most times. To show how good a new guy is, they have punches and defences just flashing around with no clear detail around technique. Also, outside of the callous masters, the serious parts with Kenichi often fall flat. There is only so many times he can man-up over the same thing that can be presented before boredom sets in.
Overall, Kenichi is good, but the early season is definitely much better than before the anime ends. Not sure if the manga has the same problem.