This. Usually Mary Sues have that forced air that made them Mary Sues. Tohru, on the other hand, made seem pretty natural of being a very nice (to a fault, which the series show sometimes like when her father's family was trashing her mother) and innocent. It didn't feel like she was made to be a self-insert for a romance for Yuki and Kyo, hell, she was pretty ignorant of their feelings for a long while.
I liked this series until it introduced too much of that romance bullshit that plague most shoujo titles. It would've been a better end if Tohru left the family, died, or a harem end with Yuki and Kyo.