Only flaw of this novel is hehuan arc and it's flaw because people are obsessed with age and prodigy, and author choose this arc to tell that protagonist will not always be under 30 and time calculation will truly be according to immortal rather than that of mortal.
And another thing if anyone is reading it for unique power system and martial arts,
then go ahead it will not disappoint you.
Edit-Don't listen to @Darknorth he didn't read this novel carefully.
Power gained from other world will not get Nerfed, on the other hand it will give mc more means and better foundation.
All the power of other world has different aspect of focus in qi , essence and spirit,
And mc can get go to new world every major realm and latest world (third world)
Can directly point to nascent soul from foundation stage and it's martial arts world.
Why do these cn mc has do these kinds of thing, if they hide their power they will hide to the point of costing their life and if they don't, they will staight up tell the government about their power.
Behaviour of mc is so frustrating.
Those who are watching for uniqueness should get motherfucker transparented eye of ghost, then whats the difference between him and others are.