“Matt, who had seen guests come and go for many years, knew there were two kinds—those who thought the hotel was a dreadful old barn of a place and those who thought it charming and quaint, so quiet and restful.”
I'm assuming here that so is not used in its sense as an intensifier. This threw me for a bit of a loop because I didn't think that so could be used to connect anything below the level of a clause. In fact, that was one of the properties that I thought distinguished coordinators from conjunctive adverbs, the topic with which this blog started over a year ago.
It strikes me as a little odd, but the more I look at it, the less objectionable it seems. What do you think?