Martha Finley was a teacher and author of numerous works, the most well known being the 28 volume Elsie Dinsmore series which was published over a span of 38 years. Finley wrote many of her books under the pseudonym Martha Farquharson.
"Elsie on the Hudson" is indeed a good book, as it is part of the Elsie Dinsmore series. However, I expect a lot of readers will be quite bored of the constant monotone of recalling historical events. Only about 1/4 of the book concerns a storyline with the Dinsmore and Raymond family connections. I rather enjoy history, so I'm still intrigued with the other 3/4 of the book, where the characters just retell events of the Revolutionary War and such. Looking forward to book 24 next.
This series is a bit Calvinistic in its theology, and it's also a bit uber-Christian; i.e., the Christians are really, really good and the non-Christians are really, really bad. The further into the series you get, the more boring the books get because there are too many historical lectures in the later books rather than actual plots.