At the time women were still delicate creatures, and Ricci plays that well given her stature and petite frame. I, personally found her unbelievable as the character of Lizzie mostly because I would never have believed a woman with as little muscle as Ricci could have swung an ax over twenty times to kill two people. The movie created a suspicion around Lizzie and her father that they may have had a somewhat incestuous relationship, especially on Lizzie's behalf.
I'm sorry but this movie wasn't very fabulous. While I enjoyed Clea DuVall as Lizzie's sister, Emma Borden, the rest of the acting was just sub par and not that great. Ricci wasn't a believable Lizzie, and even Stephen McHattie (who played the father) whom I have enjoyed in other things (the TV show MILLENNIUM for example) wasn't that great in this. Clea as Emma was really good, disapproving where she needed to be, and a comforting and loving older sister when that was needed instead.
If you want an accurate portrayal of the Lizzie Borden trial and ax murders I wouldn't suggest watching this movie. If you are a fan of Ricci then go ahead.