If there was every a source material that truly deserved an adaption, it would be for the Song of the Long March. Truthfully, although I have my complaints, they don't disappoint with this adaption. It's fairly true to the source material (where the changes are actually beneficial to the story and character development of the other characters). They also chose excellent actors; not exactly the ones I had in my mind, but boy did the embody their characters P E R F E C T L Y. (Dilraba was pretty spot on truthfully. I'dve like to see Kyulkyung try this role. But truthfully, Dilraba 110% fits the bill. I couldn't see it any other way.)
But all of the actors-- they somehow make the characters more lovable then their source material version. The side characters are a bit more memorable, and you grow to be invested in the side stories progressing as well. There's plot twists, and stuff -- but it really helps fill out each character to seem more realistic. I found myself routing for the people I hated the most.
The cast, I can tell immediately -- seem like they'll be dorky and friendly off screens. It's unfortunate that I feel like the chemistry between Dilraba and Leo are a hair too dry for my liking, (i.e. Le Yan and Hao Du seem a bit more clear cut) but truthfully... I don't hate it. It's one of the few times, if not the only time it makes sense that they're not falling into each others arms. They really delivered even more then what I expected of the main characters in a way that makes sense.
Additionally,. their subtle movements, and really minute expressions truly makes it feel like they're living the life of the character. It feels natural; generally speaking, this doesn't feel like a rookie cast. And more importantly, the direction of the show is really on point. It isn't a 100% score in my book, but I think my bar is set a little higher just given my love for the original series as well as having seen some of the other work of the cast.
At Dilraba specifically, to no fault of her own, I found myself comparing her to her previous works where she has a similar estranged character (i.e. The King's Woman), and she hasn't really been able to separate those similar archetypes apart; it's a difficult task, probably impossible even-- but it's my small gripe. She makes Changge seem a bit more bullheaded and warrior-like in comparison to a quiet, chess-sort-of-cunning that I had imagined Changge to be. She grieves, but much more...loudly yet not as deeply....if that makes any sense. If I had to explain it another way, she acts too mature for the role, but contrasts by giving Changge a more childish/unwise? reaction to some things that makes her seem like she's in a different role.
Leo on the other hand makes Sun to be a bit more cool and calculating then I imagined Sun to be (if anything I expected him to have a bigger gap like how Dilraba is), but he really really shows the trust he has in her -- as well as understanding in her then I think the source material could ever get across. He knows what he wants, but he's not possessive, despite being the cold king stereotype. It's really really refreshing to see a male lead like that. I think he shows a really good progression of just being involved on the ride to I'm really just here for my girl Changge. I think this quieter (then the already quiet Sun) version really shows why he's the best of his clan; and it's not just purely on brute strength. *wolf's whistle to the fight scenes they do give him though because ooh weeeeeeeeeeeeeeee*
Again with all of that said, I really did not hate anything about this show; the whole cast gave it more colour that made it equally if not more enjoyable then reading it. They're purely gripes of a book to adaption watcher.
And even though it's not a one to one adaption, it's not a poorly done spin off either.
It's a good balance of new and respecting the original.; truthfully I think if this was my first historical style show, or if I had not read the series first this would have easily become my favourite series of all time. But since it's not, the least I have to say is this is an A-tier drama with S tier acting, S-tier directing and also most importantly S-tier source material. Please watch it. Also please consider reading the manhua.

I haven't slept yet, (in fact just binged up until episode 33 until my internet went down).. but I'm itching to get back to it. Somehow it brings me back without giving me horrible cliffhangers to hang off of-- which P.S. I'd say is the same level of draw that the manhua gives.