Sefer Ha-Hayim Blog said, "The truth, that Sefer Heshbon Ha-Nefesh was written by a maskil, is still surprising."
UNFAVORABLE INTERPRETATION I:
Surprising because.... a masikl wrote a book? (Ha! Next you'll tell me misnagdim daven.)
UNFAVORABLE INTERPRETATION II:
Surprising because.... everyone knows the haskalah produced nothing useful. (Besides convenient targets for pious frauds, of course.)
UNFAVORABLE INTERPRETATION III*:
Surprising because.... everyone knows the maskilim never worried about ethics or about the lives of religious Jews. (They were all pig-eating, mixed-dancing, J-date using, heretics)
Surprising because.... the yeshiva establishment never accepts or endorses books written by less-than-perfectly-religious authors.
* Note to II and III: The haskalah movement was all about Jews abandoning their exclusiveness and acquiring the knowledge, manners, and aspirations of the nations. So it shouldn't be "surprising" that a maskil might write a book in which Jews - especially religious Jews - are encouraged to acquire ethical and virtuous conduct.