The thing about Persona 3 and 4 is that they present themselves as happy and cheery, but if you delve into the characters, and they're anything but.
Look at Nanako and how lonely she is.
Or how Kanji is confused about his sexuality.
The problem with P4 are the s-links. In P3, you do extremely questionable things in order to gain that rank up, whether it's telling a little girl to run away from home, or telling your kendo partner to keep going to practice even if he risks the ability to participate in sports ever again.
P4 doesn't have nearly as questionable content, which is disappointing, but I would dead pressed to describe it as cheery.
I really liked the Death slink, because it involved a really interesting theme. That is, until they turns it into "help me deal with my problems".
But then, I'm still in the I prefer P3 to P4 camp even if I acknowledge that P4 is the better game.