An interesting mix of exciting action and Machiavellian politics, interspersed with sentimental sequences. It gets kind of bogged down and repetitive around two-thirds of the way through, but regains its stride for the last several episodes.
I learned a few things about Korean culture and history and am now interested in learning more.
You have to suspend judgement and just go along with some of the unrealistic consequences of all the violence. Major characters keep getting shot with arrows, stabbed, or beaten to a pulp, and then miraculously recovering in no time at all.