It's incredibly repetitive and the concepts are too abstract.
The trend from the first omnibus volume continues: New threat, the immune cells fight the threat, they lose, a new concept is introduced that triumphs over the threat and everyone is happy. Rinse and repeat *yawn*.
The design of the characters is cool, but it is so far removed from the actual cell they are supposed to represent, which is emphasised by the far too frequent text boxes, that explain the functionality of the cells in the most robotic and monotonous way possible. It's frustrating.
Now that the manga is finished, I've learnt a bunch of new names, but I couldn't really explain what they do, apart from associating them with a certain character from the story. When the stories themselves are not exciting, the book becomes less than the sum of its parts.
It looks pretty but is quite shallow and I can't recommend it, even though I do like the premise.