So, I watched this because it's so highly rated, and while I definitely did enjoy the show overall, if you aren't very familiar with governmental and judicial systems and lingo, it may be very confusing. I am someone who isn't versed in the previously stated, and I got lost in the show quite a few times. Not to mention the fact that there are SO many characters in this show, so between memorizing everyone's name (some of which share the same surname), the lingo, and the fact that it's fairly fast paced at times, made for a confusing situation.
Now, that is just ME, and could be my attention span. But I've watched plenty of other procedurals similar to this and wasn't that confused.

Aside from that, I will say that I think the whole first season overall was fantastic and I would suggest it to someone who likes crime thrillers and police procedurals. Bae Doona is killer as ALWAYS, and Yoo Jae Myung always plays the best stuck up jackass (iykyk itaewon class). Same with Lee Kyung Young in Vagabond too! The twists and turns were incredible and I love how the director set up everything perfectly and then tied it all together at the end!