Saikoroshi - an interesting and introspective chapter grappling with the weight Rika's lifetimes have had on her perception of herself and others, as well as posing a question of whether a "pure" happiness is as valuable as a happiness earned albeit one you have to sin to achieve
Hirukowashi - a fine chapter if you enjoy the club's usual hijinks with some odd moments but overall, its passable, not the quality of the main chapters but still a servicable entry
Batsukoishi - hmm yes 3 grown men fantasising about humiliating pre-teen and teenage girls, not creepy at all. Easily the worst chapter in the whole franchise, even including the mess that is Gou and Sotsu
Ultimately, is this pack of chapters worth it? maybe if you really enjoy Saikoroshi and Hirukowashi but if not, either make sure to get it on sale or just watch the anime