1) So much potential initially. The LN had interesting thematic areas initially which seemed interesting. There was time travel, mysterious origin of MC and that chick in the pearl and so on. After reading it till ch 600, I can say this without doubt that it all turned absolute stupid crap.
2) The MC and the villians are all soooooo stupid. They are all basically pyschopaths and sadistic egotistical genocidal maniacs. The MC basically kills of 70, 000 innocents just because one of the idotic young master of the rival clan kidnapped the MCs grandfather and aunt (although they treated them nicely).
3) It seems all the good luck of all people seems to fall in hands of MC. He has phoenix blood, Phoenix Ode skill (high level skill), Two absolute heaven defying treasures which are just TOOOOO OP, he has evil god's blood (INCREDIBLY OP), he has evil god's seed (water and fire seed which make him 100% invulnerable to any type of flames/fire attacks from ANYONE as well as water based attacks invulnerability from ANYONE), he has dragon god's blood, dragon god's marrow, he has OP sword, skills and techniques from God realm from an OP teacher who resides in one of the MC's treasures and the teacher of MC herself is too OP. Apart from this, do not get me started on all the other different treasures and skills which just seem to fall on his lap and also his luck with the ladies. It too much.
4) The MC is basically a pervert, he raped a women who was basically completely defenseless and she then becomes an expert later on but then her fate turns out really pitiful bcoz of MC's rape gets her pregnant and she is crippled by her own sect master for going against sect rules and having relations with man (not allowed in her sect) and she is kicked out and is missing.
5) The MC is basically so powerful with his divine skills and abilities that he can defeat someone who is two whole F'ing realms higher than him (20 stages above him). Even though author repeatedly stresses that the difference between two realms is like heavens and earth.
6) the cultivation system is never really explained at all. How is earth profound realm any different from sky profound realm except that they have more profound energy??... There is almost no distinction between the cultivation realms except just more energy.
7) Author made MC so OP from the start that he is now struggling to keep him at lower levels deliberately so that tension can be retained in the novel.
LIKE SERIOUSLY, in chapter 500 or so, MC is rewarded tyrant profound pill which if taken then it can help the cultivator no matter which realm he is in to immediately break through to tyrant profound realm. Currently, MC in chap 500 or so, when he is offered this pill is already in 10 stage of profound sky realm and he can already kill 8th stage tyrant profound ream expert. If he had taken the pill, then he would have immediately become an overlord of entire profound sky continent and demon realm. BUT, he just gave away this pill to some no name relative who had appeared for no more than a dozen chapters for no reason at all.... WTF. I mean, its fine if author wishes to deliberately keep the MC weak to retain tension but atleast do it in more logical and rational manner.
8) Author always finds ways to justify the cruel actions of MC in good light which even a person who had IQ lower than 10 would not accept. I do not have any issue with anti-hero MC or even villianous MC. But author constantly tries to portray MC in heroic and just way which just feels annoying and frankly, it just feels like author thinks the readers are just plain stupid.
Objectively speaking only talking about Desolate Era, it is a decent novel till volume 11. Afterwards, it starts to become boring. The fights described in the novel are poorly done with just bang bang sfx and no imagination put to them at all. Secondly, there is lack of any proper story. And readers will start to feel this towards end of volume 24. Volume 24 is when the civil war in Grand Xia Dynasty ends. After that till volume 42 (till what I have read), there is no substantial story AT ALL. Its just usual progression with no real substance. The MC only wishes to resurrect his lover. But for this to go through 20 WHOLE volumes with 30-35 chapters in each volume is asking too much from readers. This is one of the flaws of all IET novels. They are usually too long with story development happening too far and few in between the chapters. This happened in Stellar transformations, Coiling Dragon and Lord Xue Ying. Plus, if you have read other IET novels that you will know that all the MCs are interchangeable. There is no difference in the personalities of MC in ST, CD or any other IET novels.
You could put Qin yu in CD or Linley in DE and it would hardly make any difference. Plus, the entire story is just about MC. There is hardly any interesting side characters. If you are looking for casual read go on ahead, the LN is OK till volume 24. After that it just gets progressively worse with author just expanding the power realms and world building as story goes on. Oh you think Daofather is most powerful??! Oh but wait till you reach volume 24 to realize that they are nothing but regular guys when you go beyond three-realms.... WTF...
The author goes to a whole lot of trouble to make various plot points which can be then used for future story. However, they are rarely touched upon. For instance, the mystery behind the annihilation of the MC's mother's paternal clan. It is mentioned on and off in few phrases through out but it is always the same content. After it introduction to this plot point in chapter 40 or 50 it is hardly touched upon and now we are at chap 450ish. This is ridiculous. Secondly, the some where down the line, MC starts aiming to build strongest mercenary corp in continent but that too is hardly ever mentioned after that aim of MC is mentioned. Thirdly, in just one chapter, author completely blows open entire world building. I.e. When MC's soul and sword spirits merge in chap 300 or 320ish (don't properly remember). The Sword Spirits communicate with MC and tell him that they can increase in power after he absorbs chaos energy. But unfortunately, this world (i.e. The plane of existence in which MC is currently) has meager chaos energy. Also, the cultivators of this world are too weak in strength. This gives an indication that after MC becomes strongest in this world, he will probably ascend to some higher plane (my speculation) (and bear in mind we are already at chap 450ish). This is too long content without any plot development.