The Tale of Briar Bank is a myriad of things; cozy mystery, historical fiction, and fantasy to name the genre blend for one. Beatrix Potter joins the readers in the Cottage Tales series, as a sort of lady detective light - but she's not the only one helping solving the mystery at hand. Her fictional animal characters, the ones you're probably familiar with through stories such as 'Peter Rabbit' and 'Ginger and Pickles' are also there, and they have stories to tell. That's part of the fantasy element right there, although there's one more 'traditional' bit of fantasy too, to give you a hint it's a creature you might find in an epic fantasy but not expecting to find in a cozy mystery set in 1909.
The mystery itself isn't that complicated, nor is it particularly grisly. There's your cozy factor; there's a death, a few suspicious people, and a discovered treasure with a possible curse over it - but ultimately it's not a particularly intricate mystery, nor should it be the reason for picking these books up in my opinion. On the other hand, the sense of a whole community is I think a good reason to do so. If you enjoy seeing how a whole community in the Edwardian era would live and breathe in a sort of village setting, you've come to the right place. There's love, drama, unpaid bills, hidden identities, and some of the outsider experience through Potter - buying a farm in a small-knit community and becoming a part of said community.
Another reason this is so much fun is that Susan Wittig Albert definitely did her research before including Beatrix Potter into the mix; many of the things surrounding her character is either true or based on facts, therefor it's in many ways fun to read as someone who's interested in Potter herself. It's set right when she's buying a second farm, and deals indirectly with her complicated relationship with her mother, as well as her slightly tangled experiences with love.
As most other books, there are flaws - one of the main ones for me being the constant presence of the author in the book. Don't get me wrong, I enjoy the occasional interlude of an author coming out to say something to the reader, but not constantly. There's quite a lot of telling instead of showing - like a character saying 'He's a baker, so therefor he has flour on his clothes' (my own example mirroring something similar in the book) - when it's clear to both characters who are talking what the occupation of the person they talked about was. It might not bother others as much as it did me, but it's definitely there. Then there's the feeling of the book possibly taking on a bit much; there are several puzzle pieces, all individually interesting, but it just feels a little underdeveloped in each part so that the entirety isn't as neat or pulled together as I would've liked.
All this said, it was certainly a very enjoyable reading experience. I enjoyed traveling back in time to the early 20th century and experiencing a little bit of farming life, gossip of the village, seeing a fictionalized Potter dealing with loss, love, drama, and prejudice, seeing her animal characters come to life. It was all good fun, and I'd say if I happen to come across another book in the series I would gladly pick it up for a bit of fireplace-reading.