I started out pitying Thomas Senlin, the mild-mannered headmaster out of his depth in both marriage and the hectic surroundings of the Tower, thrown into confusion and despair at the loss of his wife. Soon, however, he developed in a believable way from the shy, rational, open and trusting man he started out as, into someone altogether stronger and more wily. Spurred on by hope, Senlin stumbles through his adventures and learns more about the Tower as he goes. It's clear from the beginning that this isn't a safe or cosy place, and there is a certain amount of violence including the occasional gruesome moment, though none of it seems out of place considering the circumstances. I liked the quotations from the Everyman's Guide to the Tower of Babel at the start of early chapters, highlighting the disconnect between the guidebook and reality, the version Senlin has taught in his school and the version he experiences.
My only slight reservation was the change of story-type, quite a way through. For well over half the novel it had a classical feel to it, with Senlin moving through his quest in slightly detached episodes, each with its own location and cast of characters, almost like the Labours of Hercules or the Odyssey. Suddenly a character reappears and with them comes more of the cohesive plot structure of a modern novel which gave me a moment of disruption, having got used to the previous style, and I also found I had to refresh my memory on the reappearing character as they had been gone so long. On the whole, though, this is a fabulously gripping start to a series. Senlin is a likable likeable character and the Tower is a fascinating setting: I can't wait to return for the second instalment.
If you're in the mood for another inventive steampunk-tinged thriller that's the start of a series, I can recommend [[Grandville by Bryan Talbot]]. It's a graphic novel populated with anthropomorphic animals, so a different approach but equally good on detailed world-building.