Great cast, great plot, great acting, great pace, great wrap-up. A very complete package of everything. Nothing really missed for me. The action sequences were class. The relationships and network were inspiring.
Among the things that this series did better I would like to mention my personal favourite -
1. Car chase : Honestly I have watched many kdramas that have these gangs and gangsters, but it's always hand on hand combat and/or weapons. But a car chase is very rare and the one in this series has been done greatly compared to the korean average.
2. Action sequences : Nobody pulled there punches. It sure looks like it. The different weapons and techniques are amazing to watch.
3. Backstory : This wasn't overdone with MSG that somebody killed somebody's someone so the son or daughter of that person plots revenge. The background of the story is very tangible in this drama.
A very few misses that won't be annoying -
1. Some characters you'd like to know about what happened to them or so was not really explored. But it's fine as long as you're not much invested and how can you be considering it's just 8 episodes.
2. More brawns than brain. Could be a turn off for some or could be just the thing for others.
All in all as i already said, it is very complete.