The drama has a very good start. FL gets transported into the past and undergoes through a dramatic character development transforming from a hoodlum to a more mature, empathetic, and thoughtful young lady. But, the drama does not do a very good job keeping track of all of the characters. FL's interactions with most princes are superficial making them very forgettable. For the most part, they seemed more like place holders to make Ruoxi look good, rather than serving an actual purpose.

The romance is very long winded and takes forever to develop. After it finally ended at around episode 15, the writers decided to bore us with episodes upon episodes of Ruoxi and the 4th prince pining after each other without any movement on that story line. The last 15 episodes were unbelievably boring. There wasn't much political intrigue or romance either. People were just talking, reminiscing, and pining after each other. Even though the drama only has 35 episodes, it could've been wrapped up with a much better pacing a lot sooner.

EDIT
I watched the last 3 episodes and I ended up skipping through most of them. I stand by my opinion that the drama is unnecessarily long and boring. Lots of scene could've been edited out to improve the pacing. The acting was very stiff making character interactions look forced and unnatural. The camera work was goofy and made dramatic scenes look comical. After the last episode, I did not feel the same sense of tragedy and loss I felt after watching the Korean "Moonlovers". In 2011, "Scarlet Heart" was probably ok. But considering how much Chinese dramas improved in the last several years, it did not age well.