I don't like to write bad reviews but in this case the show had the makings of something much better than it turned out to be and for me that's sad.
Your main couple FuJiuYun and Qin Chuan seemed to come out of nowhere to me at the end. FuJiuYun obviously loved her from the beginning but she didn't even know he existed, and when she did she thought he was more an annoyance than a love interest. By thee time things might have started heating up between them they went their separate ways for a while and she actually spent more time with her childhood sweetheart and the 2nd prince than she did with him. Then in the span of one moment she turns around and states he's the love of her life and she wants to die with him! it had almost no build up and although the actors where great the story left potholes regarding their relationship that could not be covered up.
Another thing that could have been done better in my book was, the show was called 'love of thousand years' yet only on a few occasions did FuJiuYun even drop hints that he had been watching her that long. There were no flashbacks into past lives, no discussions among the immortals about how long he had been watching. Nothing! it was like the past thousand years of him watching and protecting was something insignificant and could be pushed under the rug. Why bother including it in the title if you aren't going include it in the show?
The third thing I had a problem with was the end. Now I haven't read the book so maybe that makes more sense but the show didn't. Did she go back in time? was it a dream? did everyone come back to life in some alternate universe?......if she went back in time why didn't her face change back again?........it just didn't make sense. As for loosing Qin Chuan her memory of FuJiuYun, again it didn't explain why that would happen. To suddenly get pulled into the painting and find him there was a semi good ending but it seemed to concentrate on everyone but its main leads in the last episode.
The music and costumes where great and the acting was super. The ML and FL had good chemistry, in the little time they had their relationship. It was the plot that let it down. I hope I can see these actors again in something that shows off their skill properly.