What is it?
Shigeno Goro is now a senior high school student and he makes a fresh start a Seishu High. One problem: not only does Seishu not have a baseball club, it only has 10 or so guys attending it (since it was recently converted from an all-girl school). Shigeno takes this ragtag group of newbies and hidden talents, and this new team tries to make it all the way to Koshien, battling old rivals along the way.
What's good about it?
Oh the passion of youth! This is sports anime incarnate. You either hate it or love it. I'm in the love it category. Most characters from previous seasons make appearances, albeit much shorter ones. Full of willpowed drama.
What's bad about it?
This is probably the weakest of the 3 seasons so far. Shigeno (and the series) kind of starts over from scratch after leaving Kaido. He starts a NEW team with a full cast of NEW characters, but since the show has been about Shigeno's progress, this seems counter-intuitive and didn't sit well with me. The new characters are not great either. The season ended on a climatic note so I'm hoping there's another season left in the series. Major should've focused a little more on non-baseball matters. Namely, school and social interactions (get a girlfriend!).
I'm a sports anime junkie so I'll never turn down a season of Major, but I know I won't be watching Major 3 a second time. In retrospect, season 3 will be remembered as the filler season in between Shigeno playing with Kaido and going to America to play (if there's a fourth season). Probably an above average sports series(mostly since most are not very good), though well below it's previous efforts.