Really, really great series. Tho I wish we would have gotten a little bit of Sekigahara as a bookend to the series, the explanation by Toronaga was good enough for the non-action movie addled among us.
As for whether Toronaga was a villain or not, if you go by Ieyasu -his RL counterpart- I'd say he wasn't really. At least in comparison to the other 2 great warlords of the period Hideyoshi (Taiko in this series) and Nobunaga (who Mariko's father(?) killed in the series, leading to her family's disgrace). Sure he laid the groundwork for Japan being closed for 200 years, but it was his successors who did most of that work, not him.
I'm not the biggest expert on this period of Japanese history, but of the little I do know I'm kind of partial to Nobunaga out of the 3 of them. Tho it's hard to know how anything really was after the haze of history as told by the winners and 400 years of time are in the way of the truth.
I also like that the legend of Musashi takes place during this same time period and he was contemporary to many of these characters' RL counterparts. For anyone interested in the period, Eiji Yoshikawa's (fictionalized) account of his life is a must read.