This is the first of the Cities in Flight novels by time of setting but the second in order of writing. The only other work I've read by Blish is the far superior A Case of Conscience. This book is written in a style like Heinlein's but it reminds me very much of the Foundation series by Asimov, which I don't necessarily consider a good thing. There is far too much standing around talking and the great mystery that is reveled is something that you know is coming.
However, Blish is talented enough that I want to give more in the series a go. Not exactly a bad book, but a little disappointing.