This was perfectly fine, all around. It's cute and it works and if you need your shoujo fix this will do it. It's a little unfortunate that this is coming on the heels of Too-Perfect Saint, which executes a very similar idea in a much better way, but that's not really this anime's fault. I give the premiere a 3/5.
I won't be watching more, but before I go, a prediction: the sister faked her death and will turn back up disguised as a man.
Well, your sister dying in an accident on the way to marry the guy, who wanted you in the first place, and your parents sending you as a replacement is certainly a way to get betrothed to your sister's ex. I wonder if Anastasia may have survived somehow.
To my surprise, I quite enjoyed the premiere. Yes, it was tropey in the way all Cinderella type stories are, but I didn't mind it. The maid is shaping up to be my fav. Hopefully, it turns out to be a decent fantasy romance.