I have just recently finished catching up to this series. Shingiku Nakamura often receives a lot of criticism from the BL community for her art, and in the case of Junjou Romantica (but not so much in the case of Sekaiichi Hatsukoi) the aggressive seemingly rape-like initiation of some sexual encounters, due to her ukes' tsundere-prone reactions to love. People have begun to speculate, with Junjou Romantica's third season on the horizon, as well as the upcoming OVA for Hybrid Child, that perhaps the author, like her characters, has pre-existing connections with the manga and anime industry, leading to her unparalleled success the field, despite the neglect other BL series' receive in being translated to the animated platform.
However Sekaiichi Hatsukoi and Junjou Romantica have qualities that make them classics, and masterful in their own right. One character, for example, is never thought of without their corresponding partner; such is the nature of Shingiku's Nakamura's characterization, where a single person's role in the story cannot be advanced without the growth and intervention by their significant other as well. Although I tend to not enjoy episodic stories, and I prefer arcs or one continuous train of thought, the story benefits from the continuous situational variation, because the focus of the story is still consistent: the growth of the pairings themselves. In that way, the simple goal of strengthening love is expanded upon, agonized over, and glamorized extensively in this hot-and-cold, sexy, laughable, and comedy-filled compilation of the makings of a First Love.
It is very difficult to pinpoint the qualities which make Sekaiichi Hatsukoi different from Junjou Romantica, though most every fan would agree there is a distinctive different in vibe between the two. I attribute this largely to Nakamura-sensei's growth in storytelling capabilities. The universe of the pairings seems smaller, more focused, and their struggles more detailed and meditated upon. As a consequence, the story feels much more unique, and isn't quite as sporadic and variant in emotions and struggle as Junjou Romantica(qualities which I think give Junjou Romantica a more classic feel as a BL). Overall I enjoyed Sekaiichi Hatsukoi more as a complete universe; the characters collectively are distinctly more realistic, profound, and insightful. New BL fans may not want to give this series a shot because of its art, or because of growing hate-groups for Shingiku Nakamura's work and success, though I do believe she has established herself as a classic author. Her stories show love in BL as more than just a fling or more than just fantasy, but something that really takes itself seriously. Back when she began Junjou and Sekai, that was not the case. Sekaiichi Hatsukoi is warm-hearted and addicting. I would recommend it even today, after I've read hundreds of contemporary BL.
Sekaiichi Hatsukoi