I'll put individual reviews on each book, but here's my overall feeling.
I loved Leena - she was hands down my favorite and the one I connected with the most. Through her side novellas (and her interactions in the main books), it gave the story a different feel.
The main books focused so much on Rhen and Jinji's relationship; not necessarily the romantic elements of it, but of the two as a whole. Leena mentions at one point how odd it is to see one without the other and I think that's a fair statement. By the end of Book 3, despite their various trials, they are no longer individuals but two halves of one whole.
Leena's perspective however gave a broader idea of what the vision Rhen and Jinji wished to create could effect, especially for the Ourthuri.
Meanwhile as to the main storyline, I enjoyed it. It was quickly paced and while it got a bit repetitive reading the same scene from two (or three, if you count Leena's novellas) different view points, I appreciated the deeper understanding it gave each character.
Some common issues arose (miscommunication, misunderstanding, etc), but at the least they all admitted they could have screwed things up worse if they didn't work past that stuff quickly.