One could write about how this is just a continuation of original series and has continues with the same format of "adventure of the day". For the first half, yeah, you can say that. Then something happened for the second half, they actually wrote a multi-episodic story with some major character development. Thus I will focus on that part.
Like I said earlier, the first half was the standard, but the second half was very good. It all starts with Natsumi getting an invitation to join a police special forces group. This made all the her co-workers/friends, esp. Miyuki really question
how each other are part of this group. Even Ken started having doubts about himself because of a situation with Miyuki. Even the ending strengthens the characters with each other.
I do enjoy this series because they characters are adults instead of being there as comic relief for junior high/high school students. We adults have problems also.
So to break it down:
Story - 8: I had to give it an 8. The average of the first half and second half.
Art - 7: This will never be as good as the details from the OVAs of the first season. The artwork did take a hit. I wish more time was given to make the characters and scenes look better at times.
Sound - 7: Felt overpowered by the background sound. I do miss the sounds of the motors that Fujishima puts into his creations.
Characters - 9: All were great! We got to see more of everyone, including the rookie Saori and Nakajima's dad and step-mom.
Enjoyment - 9: Of course. Just seeing an adult cast in a slice-of-life series was worth it.
Overall - 8: It had it's weaknesses and strengths. You will enjoy this a bit more if you enjoyed season 1.