A very nice concept stands as basis for this show's plot. Nice and original.
That should be enough as reason for a high rating. However, for the rest I might say that the chance to have something epic was just wasted. Pity...
The cast is good, the acting was more than convincing, the music good, also the CGI was well developed, but it was the story that at a certain moment started derailing towards a complete, confused anarchy. The solidity of a story stands into the presence of a structure within which the story itself moves. The structure was initially present, but episode after episode it was simply dismantled and the story potentially could turn into whatever without any logic or sense. Funny thing is that the final itself was "explained" as a consequence of the rules governing the interaction between the two worlds: someone should explain me at this point why someone had to disappear, while the only reason behind the reviving of another one was that the W. world started working independently... So, both of them could have been survived, because there no longer were any rules. Hurray for the fantasy, that's sure, but not for ridiculousness. To explain what I mean, I might say that a good webtoon is the one which has an actual story to tell, a credible one, where the rules and the boundaries are clear or it is just a waste of paper and ink.
In addition to this, some nonsense hit the villains' characters. I understand that the predetermined fate for each of them should be the reason for some illogical actions taken by the same. But the continuous obsession towards the leads, at a certain point became paradoxical and not well credible.
The free will that the W characters start showing and which should be the main reason for their changing from toons to humans, is itself incredibly not explained, not clarified, thus not convincing. Why, for what reason all of that happened? Why did they start acting and choosing on their own and no longer following the plot decided by their creator?
Who knows?
Pity, really...