This book was written with a real eye for detail. Little things, like how someone would have fixed a baby's bottle in 1616, were fascinating to me. The descriptions are vivid and excellent. I felt like I had a window into how a poor woman in Germany would have actually lived during that time period.
I would say the book is more literary - it reminds me of Thomas Hardy in a way, with its focus on realism and detail. The author really puts you into the grit and grime and daily existence of Katarina and the other characters.
There is a really nice, slowly developed romance, but there's much more going on. It's a book about relationships - between Katarina and the baby she is forced to care for, a former lover, the old woman who raised her, and more. There are action elements scattered throughout, too, with a majority coming in the final fourth of the book. There are a couple of love scenes, but they're tasteful, emotional, and serve the larger story.
My only caution is that the book is a bit slow in the first half - actually, the first 20-30 pages move along, then there's a period where plot takes a backseat to character development and a description of the characters' daily lives. But things pick up substantially around the halfway point. You kind of have to go with the book's rhythms - like I said, it's more of a literary read.
If you like historical novels and details that paint a portrait of what characters' lives were like in centuries past, I highly recommend this book.