I appreciate the attempt, but...Ryukishi07 was better at writing horror.
Lucia is a hardcore tsundere, since she gets angry at and beats up Koutarou at the slightest offense. Her rigidness, strictness and physical strength are perfect for her character. Unfortunately, her route does very little at making her respectable beyond turning her into the lowest common denominator.
She struggles a lot with her power during the route, but her stubbornness keeps her (and the plot) from reaching any satisfactory conclusion, and seems to make the story drag out. This actually makes her a worse character than Chihaya (while her personality didn't change much, at least she was assertive and tried to help the plot move forward in some respect). Lucia seems to want to fight against plot progression, and it really hampers the route.
Another problem with this route is the multiple perspectives. It's still clear that Koutarou is the main character of this story, but there's way too many focal characters. This not only destroys the focus of the story, but when the story is supposed to be told in a first-person perspective, it tends to be both confusing and pointless when we're learning about conflicts that do not apply to the main character. It works better in movies, but it never works in literature. It probably would have worked better if it were told in third-person omniscient, but Ryukishi obviously had no choice.
My last criticism lies in Ryukishi's attempt to replicate the nakige structure. Now, he's written Higurashi already, so it shouldn't be that hard to replace horror with sorrow, right? Well, Ryukishi felt it should be exactly like Higurashi, and threw in horror elements that felt out-of-place and, in the end, unnecessary. He's not bad at the emotional parts, but obviously Tanaka and Tonokawa are much better at writing this sort of story. One thing I can give him credit for, however, is how he managed to make going out with a hardcore tsundere like Lucia enjoyable. That scene was perfect, and if the rest of the route was of that quality, it would have fared much better overall.
As for what I like about this route, there were a few background tracks that were well-placed and beautiful to listen to. The CGs and fight scenes were also quite impressive, and this route pretty much cemented the awesomeness that is Shizuru. Sasuga Shizuru~ <3
There are a few more things I could say, but they're more nitpicks than anything. Honestly, this route feels like Ryukishi tried to write something he wasn't comfortable with. With a bit more practice, he might actually write a good nakige someday.
Man, I can't wait to play Shizuru's route now!