Personally, my favorite thing about the book were probably Simon's thoughts, because they were very true to his character and highlight everything that I like about him. Like when he is put in custody, he starts thinking "what would Aniki do," but instantly corrects himself, telling himself not to be too bold and to have self-control because of the power inside him, and that even though Nia has changed and no one is by his side anymore, "I am still myself."
And when he is in prison, in the electromagnetic jail cell across from Viral, and Viral initially thinks he's given up because he's just sitting there silent, but what Simon's really doing is thinking, his thoughts going round and round in circles, yet he keeps going at it to dig in deep inside his own feelings and carve out an answer like he carved Kamina's statues, concentrating to the point that Viral could see him glowing with Spiral Power. I'm highly tempted to translate these two-and-a-half pages of Simon just thinking, I love it so much.
I also loved his overall attitude after he is arrested and during the trial. He just has a quiet dignity throughout it all. Examples:
-He asks to be let off the Ganspinner right in the middle of the mob in front of the government building, so he could feel the peoples' expressions on his own skin, and walks through them with his head held high even as they call for him to be put to death.
-At the trial, when the Gurren-dan try to start a fight in his defense, Simon yells at them to stop before they get shot. And when Rossiu points out they aren't entitled to complain because none of them are qualified to take his or Simon's places, Simon defends them, saying to Rossiu "I'll take the blame for these seven years. That should be enough. But, if you intend to make them into a laughingstock, I won't forgive you."
And there were still more scenes that made me squee, like Simon remembering to keep his promise to Leite's children, when he tackled the Ganguard to save Gekko (the chicken beastman who tried to kill him), "I don't know who is right and who is wrong, so I'll just save everyone," and his blank look when all the prisoners unexpectedly cheer him on at the end (oh god so cute).
Oh, and how it turns out that Simon was the one who made sure all the Ganmen were sent to Leite in the first place. "As long as our spirits don't break, Gurren Lagann won't break. It's the same with the Ganmen." "I was Commander-in-chief. I had to do at least that much." XD
Another note about the trial scene- Messenger!Nia KICKS ASS. When she appears in front of Simon, Rossiu orders for her to be captured, and the soldiers shoot her with electric rounds to paralyze her. But when the electric currents hit her body, she's able to bend them to her will, make them run up to the tip of her finger, then throw the electric currents back and mow down the soldiers. o_o ...That would have been pretty cool to see in the anime too.
I liked Kittan's development, as he realizes his mistake in doing basically nothing for the past seven years, and as events escalate and he sees everyone around him doing their duty, he tries to find something that only he can do (which I feel ties in with his final sacrifice). It was also pretty sad to see the Gurren-dan realizing how powerless they are to help Simon because they'd been leaving everything to Rossiu for all those years. Hell, Kittan hadn't even attended a single trial or been in a court room until Simon's trial. The novel doesn't at all hide how unproductive the older members of the Gurren-dan have been, but that just makes one appreciate their return to glory at the end all the more.
I also liked the inclusion of the character Douma Raachia (not sure how his name would be spelled), a young soldier who was put in charge of guarding Simon when he was in custody. Rossiu gave him permission to shoot Simon if he tried to escape, but Douma was hesitant because he remembered seeing Simon defeat Guame on a screen in his village, and how Gurren Lagann gave him hope back then. Then it turns out Rossiu knows Doumu's name, even though they'd never met face-to-face before and Doumu didn't have a name tag. Rossiu just takes care to remember all of his subordinates' names (wow, Rossiu, wow). I thought this gave a nice insight into the mind of a citizen who wasn't raging over his destroyed house or something. And then Douma makes another appearance near the end, helping the citizens get to the Arc Gurren safely, trying to fight against the Mugan, and getting excited again when the Gurren-dan appear. :D
Speaking of which, the novel is fairly sympathetic to Rossiu's side too. It repeatedly stresses how effective a leader he is, and how he's taking on so much responsibility at such a young age. And there was Leeron's "crystal" metaphor which amuses the Japanese fandom so much. XD "Rossiu is hard and beautiful like a crystal. Therefore at times he makes harsh decisions. However, that crystal may look hard at first glance, but is weak to impacts from a constant direction."
Though, I can't help but wonder if things would have turned out better if Simon hadn't been arrested. Before Rossiu came to arrest him, Simon was starting to form plans in his head for what to do next and still believed that they'd be able to overcome everything as long as they didn't give up. Then Rossiu handcuffs him and shows him the state of the populace, and Simon accepts being used as a sacrifice if it would mean saving lives....if it weren't for the rioting citizens, there would still be tension, but I think they probably could have worked together. :/ But I guess that's partly Simon's fault too for acting so rashly in public, fanning the flames even though he thought he was doing the right thing...gah, nevermind. Simon wasn't made for politics, so maybe the situation was inevitable after all.
But whoever said on 2ch that there's no insight into Kinon's thoughts must not have been reading very closely, because I recall at least three scenes that were from Kinon's POV, which is more than what Yoko and Leite got. I was amused though that Kittan and Yoko were already sort of flirting near the end there. XD
Hmm, what else...
Some plot-holes that were cleared up:
-We find out where Boota has been the whole time. Up to the part where Simon is put in custody, he was hiding in Simon's clothes. Simon decides he doesn't want to bring Boota to the trial with him, and presumably leaves him behind. Later on, Boota manages to survive the attack by the moon beams on the government building, and wanders around the city looking for Simon until he catches Leite's scent (when she is driving around delivering the Ganmen), and jumps into her cleavage. And there he stays until he is reunited with Simon at the end. XD
-A part of the giant computer that they found after the fall of Teppelin was locked away. That was Rossiu's motivation for making the living computer, Lord Genome Head, because he hoped that unlocking the computer would answer all of their questions. This was also the reason why they were able to find Arc Gurren at such a convenient time, because activating the Lord Genome Head gave them access to new realms of data. Leeron sent some of this new data to Leite so she could make the Ganmen reach their full potential as anti-Anti-Spiral weapons. Leeron also used the data to create the simulation of the moon crashing into the earth.
-In the novel, Viral didn't get into a fight with Simon until the shower scene because up to that point, he had been confined in the electromagnetic jail cell for strangling a prison guard.
I might add more later if something comes to me. I've been trying to scan the illustrations, but my scanner hasn't been cooperating AT ALL. So it'll just have to be photos from my digital camera, sorry. D:
EDIT: Uh, wow. I didn't mean to write so much. o_o;