expression
for better or worse; both good and bad
Fixed expression used to acknowledge that something has both positive and negative aspects, or that an outcome is accepted regardless of its quality.
良くも悪くも、彼は正直すぎる。
For better or worse, he is too honest.
この映画は良くも悪くも話題になった。
This movie became a topic of conversation, for better or worse.
善し悪し is a noun meaning 'good and bad' or 'merits and demerits', while 良くも悪くも is an adverbial phrase meaning 'for better or worse'.
From 良く (well) + も (even) + 悪く (badly) + も (even), literally 'even well, even badly'.