Finished this manga on Viz.com (the $2 Vizmanga subscription) after watching the Anime on Netflix. It's one of those series that starts strong, and finishes weak. Final battle arc takes forever, and I was bored with it halfway through. Loses the balance of action, comedy, mystery, and slice of life it has early on (the earliest part being the best part) and devolves into one long fight with too many groups / people involved.
Author himself said in his end notes that many times he ran out of ideas and had to rush things out at the last minute, and after a certain point, it certainly feels that way. I'd still recommend reading this manga, but will say that the beginning to the middle were the best parts.
Edit: Note that Viz.com doesn't have most of the Extra (a problem multiple series on there have) so the .5 chapters and such should be read on here.