。
It's certainly true that leadership by force and intimidation has its drawbacks.
Literal
Force [and-と] intimidation [by-による] leadership [in-には] certainly minus-side [subject-が] exist [nominalizer-こと][topic-は] certain is.
A doubled 確かに~確かだ structure frames the concession as emphatic: 'certainly X is certain.' ~による ('by means of,' 'due to,' 'via') is a noun-modifying phrase from ~によって, used attributively to describe the cause or agent of something — 力と脅しによるリーダーシップ ('leadership by means of force and intimidation'). The doubled 'certain' (once as adverb, once as predicate) is a rhetorical move signaling that the speaker is conceding a point before (probably) going on to qualify it. マイナス面 ('minus side,' 'drawbacks') is a loanword compound — マイナス from English, 面 from Japanese — and a common piece of Japanese business/analytical vocabulary.