The world ends with you is probably my favorite game of all time.
The manga on the other hand, is not very good at all. It leaves out a whole lot, doesn't really get the characters personalities correct, and doesn't really had a story all together... Really, if you had no idea about the game at all, i could imagen this manga leaving you very confused as to what, who and why anything is really happening.
HOWEVER, there were some things I find somewhat redeemable. I did quite like the art style it was drawn in. It's not anything show stopping or even unique, but i feel like it fit well with the look and kind of personality of the game and looked good over all. It's also short, which is both good and bad. Good because it didn't really waste to much time, and Bad because if it were longer, then maybe they would have put more effort or been able to do something to make it better. Lastly, and i might get some flack for this but... I did like the humor. As a big fan of the game, I rather enjoyed just something a little dumb with my favorite characters. I enjoyed the derpiness of it all, even though it wasn't clever at all.
So over all, if you're looking for something that will give you a little more then a giggle over Neku calling someone a cornflake as an insult, or Mr. H missing his chance to be in the comic, then I'd skip it.