For those curious about the novel, I just finished it today. I can say that I didn't like the first part. The style felt like was trying a bit too hard going for the cutesy effect of Towelket before pulling the twist. It's not particularly bad, it just felt a bit overdone. After the events kick off and the book reaches Momen's arc, it pretty much normalizes as what you'd expect.
In regards to character portrayals, I feel they were well portrayed. Considering they're all 12 yo's, I feel the writer did a good job at keeping them within the bounds of what you'd expect a kid to say or what they would act like. Other characters like Momen, Arm-tan and the robots also serve as a good counter-balance to the innocence of the main trio.
The book is pretty much Towelket 1, so in that regard I think the book delivered graciously. It doesn't deviate from the original plot, and the elements not present in the original are introduced in a relatively natural manner (and this also isn't overdone). Do note that these elements are small details, so they don't really feel out of place in the grand scheme of things because whether they are there or not doesn't really change the plot itself of the book (or, more precisely, the original story from the game that is trying to be portrayed). There's one addition that I didn't like though, and that is that Chun didn't become Jesus after the game ends, since Moochasu never bumps into it in this iteration, and Chun effectively never does any hyper dimensional travel, nor retains the memories from everything that happened in the previous iterations
All in all, I'm not sure how many of these additions are personal, free interpretations from the writer, and how many of these may have been discussed with Kanao and introduced in the book since they weren't mentioned in the game. And aside from this, there's not really much that you would be missing if you played the game already. If anything, these additions feel like small details that the writer put into the novel to explain events that may be small "plot holes" (e.g. in the book, Conchelle/Moochasu travel inside Arm instead of using a suit in space
), or just stuff that wasn't even touched in the games but could be awkward to understand if you're being introduced to this story through the book instead of the gamePost too long. Click here to view the full text.