Of course, you should be warned that it is virtually impossible to write a review without some level of spoiler, so here we go:

This is one of my favorites. It was an unexpected favorite since I generally despise time travel plots. That being said, this one did it in a way that was not annoying: rather than the time paradox (which is why I don't like TT plots), they used the 'split universe concept' as when, time changes, a new timeline is created. Even though neither the paradox nor alternate timelines is realistic, for some reason, the latter is way more tolerable.

I was not much interested in William Chan until this show. He's not conventionally handsome, but I definitely became a fan of his after this one. Dimples get me every time.

The plot has a few holes here and there, of course (for example, how exactly did the emperor destroy the MAGICAL sect!? Aren't they magical and powerful!? Also, she tried to change the time to save her love, but then ended up killing tons of innocent mages when the timeline changed...so what exactly was accomplished there?).

The relationship between the leads is solid. Misunderstandings do not last long, they clarify things quickly, and you don't get frustrated. The SFL, despite being in love with the ML, does not do all sorts of bat $**** crazy things to get the ML, she ends up accepting that he loves someone else and even becomes friends with the FL. Same with the SML (you will end up with a bit of SMLS, but the ML is worthy so it won't be that bad). He does not try all sorts of manipulative things to keep the FL by his side and ends up supporting her happiness no matter what--even if it does not include him.

Costuming and set design was very well done. I liked the costumes of male actors especially. It was all very consistent and even with a few appreciated details such as the FL's earrings were always in the french hook style that would have been common in an ancient period (not the clearly store bought hooks, though you could see those on the other actresses). The males' wigs very rarely came off in the back (common in lower-budget productions, it must be hard to get the back to stick down, which is why they should use the braid option a la "I Will Never Let You Go" [even if its not historically accurate, in my opinion its better than the clear indication of an improperly secured wig]). Now, the actual hairstyles of the males especially left much to be desired as the ornaments over the top knots were almost always hideous (and why did the Chief Mage have a beehive for several episodes!?), but that's a minor objection. And the accessories designer was clearly in love with baskets and spikes as that was a common theme in headgear. And the FLs costume designer was clearly in love with knife pleats, but we can let that slide.

The soundtrack was good, it was used appropriately, I was not annoyed with any of it. The fight scenes were pretty bad @$$, but they could have done a better job of faking full-size armies during the battle scenes--or just skipped battles scenes altogether.

Rewatch: I've only watched the entire thing once. I've gone back and rewatched all the FL/ML scenes, but in reality will find myself watching the next scene because it is well done altogether and then will realize what I'm doing and fast forward to the next romantic scene. ;P

All in all, I recommend it--especially to those skeptical of time travel plots. There are those, of course, who would disagree, but that is the beauty of Asian Drama Land. There's something for everyone.. :D

PS. I wanted to add that I disagree with her giving up all her magic in the end and the ML is all happy because he can now protect her instead of the other way around. Pffft.