I hate the Catholic practice of confession, or to put it accurately, the Sacrament of Penance. In fact, it's not entirely exclusive to Catholicism. Chairman Mao introduced something similar when he ruled China, regular self-criticism, or jiǎntǎo (检讨). Whatever you call it, I hate it for two reasons.
Firstly, if you've done something wrong, learn from it, and make amends if they are needed. You shouldn't need someone to give a magic incantation - this does nothing - it's your actions after a mistake that are important.
Secondly, and perhaps more importantly, it's just nasty. Miranda Celeste explains why in her post A dirty little girl, her head hanging in shame (do read the whole thing):
Then there is the guilt. According to Catholic teaching, humans are born sinners and cannot help but continue to sin throughout their lives. The only way for a Catholic to atone for these sins is to confess them to a priest, do the required penance, and be absolved. As a child, I obsessively recorded in a little notebook anything that I had said or done that could possibly be considered sinful. Then, when the time came for confession, I would recite this list to the priest, my head hanging in shame, my cheeks burning. I’d do my penance and be absolved. For a fleeting, blissful moment, I would feel light and pure and holy. But soon I would sin again, the guilt would return, the little notebook would be filled up with a record of my indiscretions, and I would return to the confessional and repeat the process over and over again.
Or, as Hitchens asks succinctly "How much self-respect must be sacrificed in order that one may squirm continually in an awareness of one's own sin?".
Truly, this is an awful practice, and it is a great pity to see this app.