This is by far one my favorite animes of all time......have watched it three times
enough said on the positive side...
the only issue is...if you choose to watch it, be mindful that this anime has not ended and most likely will not end. The manga is still going, but only new ones volumes once a month for the past 2-3 years.
I know initially the author suffered some medical issues for a whole year which ended up pausing the anime, and that's why it stopped at season 3, but since then new volumes have been coming out very slowly. Its sad to see such an amazing anime die.
I started watching this anime back in 2006 then they stopped airing in 2008, well its 2013 and still there has been no word on any continuation of this series and with so many years going by my hopes have faded away. Voice actors are all grown up and most likely won't be apart of any continuation at this point even if they did make one, and Funimation said they are no longer supporting this anime and will not be dubbing the second season.