What a stinker.
I'm used to making allowances for books written in another time. Heck, I've been reading through all of Lovecraft. But this was a long, slow, painful slog. Our protagonist is the most unlikeable Mary Sue I've ever encountered. Wholly convinced he's the rightful intellectual leader among others, he spends all his time whining about how everyone else should listen to him more about what they should be doing... and not actually doing anything himself.
Then again, it was kind of neat that it prominently featured the UC Berkeley library, from which the copy I read was borrowed. (Stewart was a Berkeley professor, and Berkeley's Bancroft Library holds the George Stewart Papers.)
Not long ago, I bought a remaindered copy of one of Stewart's toponomy books, Names on the Land, and I'm still looking forward to reading it. But I'm not likely to touch his fiction again.