-everything below is packed with spoilers-
Basara is essentially a story about forgiveness. Forgiveness and atonement, rather than hacking and slashing towards the enemy, should really be the central theme (sorry English teachers that the term theme is incorrectly used here) of many more mangas. It's too easy to demonize the enemy, so I'm glad that this was a struggle that the characters had to go through and resolve. This culminates in the scene on the battlefield where Sarasa fixes her gaze on Shuri as he's announcing his true intentions of having returned to the royal family. If there is only one lessons learned from this manga, it would be to not close your eyes in fear, but rather seek to understand.
I'm reminded of two quotations, first by Cheryl Strayed in her book Tiny Beautiful Things:
She understands that attention is the first and final act of love, and that the ultimate dwindling resource in the human arrangement isn't cheap oil or portable water or even common sense, but mercy.and also from Ender's Game (forever grateful that Mr. C read this to us in grade 8):
In the moment when I truly understand my enemy, understand him well enough to defeat him, then in that very moment I also love him. I think it's impossible to really understand somebody, what they want, what they believe, and not love them the way they love themselves.
The ending is one of the most conclusive that I've read. This is a huge relief since I was frantically reading spoilers once I realized what a cliche set up (star crossed lovers) it was. Wasn't going to risk being immersed in a new world if the ending is unsatisfactory. Specifically, I'm glad that the author decided to give Asagi a happy ending instead of easily writing him off as a victimized character. The bonus chapter of Sarasa and Shuri in volume 27 showing their struggle to reconcile wrapped up their relationship nicely too. That chapter ought to be an epilogue instead of a bonus. Luckily Basara didn't win awards for nothing.
I also really respect the growth of Sarasa and how she prioritized. I was so sure that she'd pick Shuri over Asagi without hesitation, but it was in fact the opposite since she deemed her role as Tatara as more important. It's refreshing seeing a strong female lead that does her fair share of rescuing and being rescued. Of course, in the end she ran into Shuri arms when she was pressured to kill him, since by then she accomplished her objective as Tatara and could return to being herself.
This is literally the only manga that I'd complain there wasn't enough scenes with the OTP. I bet that out of 27 volumes, their scenes together wouldn't barely fill one. I'm such a sucker for them being in love and having the same belief too. There needs to be an entire bonus volume of those two kicking ass and being cute together. Another bonus chapter in volume 27 has appearances of their kids (and their friends kids), whom are absolutely adorable, I wish there was a bonus volume of their adventures too.
Lastly, another strong point of Basara is that it focuses on the inglorious parts of war, such as the civilians that gets caught up (both through getting killed in the crossfire and being burdened to fund the war), and how to deal with the aftermath. The hardest part is how to transition into a better regime afterwards, which also ought to be the focus on more mangas. Again, I must mention Ares because it's the manga that best depicts the sadness of war. Sarasa/Shuri pales in comparison to Ares/Baroona/Mikael. This is partially because a longer portion of Ares' plot was devoted to building their nakama relationship, and partially because those 3 didn't get a happy ending, damn it pains me to recall that arc.