Manga A fun manga series with a sudden, premature, ending
For the most part, The World God Only Knows is a very formulaic series based around the idea of a gamer capturing the hearts of real life women in the form of a Dating Sim game. Even by the time of the Goddess chapters, it still stayed relatively the same formula except that it gave the manga a chance to actually develop some of the girls introduced from the previous character arcs.
It was only by the time of the Heart of Jupiter chapters that the series delves into something completely different. And while this wasn't "bad," it can feel very out-of-place. A lot of folk even admit that they see the final Goddess chapter as being the actual ending of the series, because the Heart of Jupiter chapters just didn't feel right for what this manga was.
...and speaking of the ending. It was rushed as all get-out. Just look at some of the YMMV examples for the series here, and you'll see the loads of problems the ending got with some readers; the biggest one being that there was never a true final battle to end the threat of Satyr.
Manga Anime Review: Cerberus Syndrome Strikes Again
The World God Only Knows (TWGOK) starts off feeling like a light-hearted version of Sayonara Zetsubou Sensei with a ridiculous premise in a classroom setting that still somehow manages to be enjoyable. Its setting of a gamer otaku forced to be a playboy towards many real life girls makes for a well-Justified Unwanted Harem. The "heroines" (girls the protagonist, Keima, has to woo) initially feel a lot like the dating sim archetypes TWGOK pokes fun at, but each heroine receives a lot of character development and they are all shown to have their own lives and experiences outside of the time Keima spends with them. The series also has strong and lovable side characters in Elsie and Haqua. Like Sayonara Zetsubou Sensei, TWGOK gets best in its second season when it breaks out of the confines of its initial world while remaining quite silly and anchored to the original premise of a reluctant playboy/soul hunter. The heroines get more complex and realistic and the arcs get better.
The third season almost feels like a different work entirely with political intrigue, drama, and a Love Triangle. It effectively made me feel for the characters in a way that the first two seasons didn't, but TWGOK lost a lot of its charm along the way. Keima stopped being a silly gamer, Elsie and one of my favorite heroines were Put on a Bus, and I felt a little emotionally lost in where the series was going. Two major heroines of the third season carried its second half well, but I felt that Cerberus Syndrome had taken over the series and moved it in a direction far different from where it started. Deep down, I think I wanted Keima to just be a goofy asshole, I just wanted Elsie to be a silly, but very competent soul hunter, and I think most of all, I just wanted the series to move between arcs without getting tangled up in the twists of the plot along the way.
I guess this review is just as messy as my thoughts on TWGOK. I liked it, and in some places, I liked it a lot, but I feel too much time was spent trying to be something the series never was and never should have been.