Just recently finished this, it was a pretty fun ride. The only thing, I think, that detracts from the experience is the opium village arc: it was truly needless padding that did not contribute to the overall story or the development of the character arcs of Taichi and Tetsuo.
It makes me wanting the author to make another series set in either the later post-WWII Showa era (second half of the 60's-70's, 80's) or in contemporary Japan.