my take: Several books now have "if you love Downton Abbey" or "for Downton fans" on the front ... this one was surprisingly like Downton Abbey - the heiress is named Cora as well - but with more time spent on the American side of the pond and set a bit earlier.
a large cast of characters, a bit of intrigue, a bit of romance, lots of British formalities ... I admit that at first I wasn't drawn in ... but then stayed up until the wee hours because I had to see how it would end. I liked that it was a chronological straightforward story ... I read it in a week of reading a book a day, and sometimes it's just pleasing to read a story without fancy gimmicks.
My guess is that she wrote it about the same time Julian Fellowes was writing Downton. As an aside, we watched Gosford Park by Julian on the same vacation ... also worth a watch when you go through Downton withdrawal.
my source: browsing the local bookstore paperback table (and bought at Costco - for shame!)
my verdict: worth a read ... good upper crusty historical fiction