The build-up of the ending was so somber and the mood was sad for the last few chapters, then MC goes back to past and lives a lonely life for 600 years only in the hope of finally meeting his friends and live happily with them, he endures for so long and finally the heartfelt moment of him meeting his mom happens *I was crying continuously*, then when it was finally time for him to meet them, he gets mortally wounded and mother earth takes back his powers and even his memories under the pretext of him living happily as a normal person?!!!! Him losing his memories and always feeling empty inside is happy? His friends and lover living in misery due to his disappearance is happy? Why did ta perfectly normal and easygoing story end in such heart wrenching manner? I didn't even liked the character of his lover before the last chapter but even then I felt so much pity for her, so much pity for MC and so empty inside after the last chapter, the only consoling point was that the poor girl atleast found the man she loved and waited for and showed the determination to bring his memories back and if they didn't come back then making new happy memories, and forget all those years of loneliness spent waiting for him, I also wanted atleast some closure for poor Hazeline and Kim Yu-Rin, but alas no such thing happened. This ending did to me something that even the ending of Game of Thrones couldn't do, it made me love and feel sad for a character I disliked/hated till the end

As someone who just finished reading, I thoroughly enjoyed it, apart from the end. It is a harem, but not a bad one, I won't spoil who the MC ends up with though. The love interests do fight over the MC a bit, but in a more realistic way than most novels.

The action isn't as descriptive as other novels but it's still satisfying to read, power leveling is alright, nothing to really complain about but nothing to overly praise, to clear up some confusion with, the ratings for most things in the novel go (Lowest-Low-lower Middle-Middle-upper Middle-High-Highest) pretty simple but its never formally introduced.
As with most novels where the MC is or can transform into a monster/s, evolution is a big part, and as someone who quite enjoys this part, it's fairly satisfying and the dual life of the monster vs man plays a big role, not just something brushed over.
The physical descriptions are quite lacking in most areas so imagining the characters and monsters is mostly left up to the reader (both a pro and a con depending on your preference), regardless this isn't a deal breaker IMO as the focus is more on the story.
The story itself is quite good and enjoyable. It's short but the length suits the story, still would've liked a bit more to read so I could enjoy it for longer : (, but that's just me.
I didn't really like the ending so much, but I wouldn't say it was bad, just not to my taste. It doesn't ruin the story for me though so it's manageable.
Overall very good novel with a few flaws but definitely worth the read. This is all my opinion of course so you might find it different and other reviews might help decide whether to read or not. Don't take the 4 stars as being mediocre, remember 4/5 is 8/10 and I'm not the type to easily give away full scores as a 10/10 would have to be a completely flawless masterpiece that everyone alive would love unconditionally. Also this is my first review so it may be lacking in some aspects, I've tried to keep it as objective as possible.
PS; if anyone has any good monster evolution type novel recommendations I would welcome a pm.

WHY, why it was so good when I was reading it but why does he even consider raising a griffin.

It would be so wrong, it adds nothing and literally makes no sense for the level up become stronger priority brain he has.