Harm can be acceptable in this contex, however the prefered word would be shortcomings, and I thought I would just throw in a new or seldom used word (detriments) just to create some supplementary interest. Incidentally, in American English the past tense of learn is learned, not learnt, which is not a word. However in the Queens English learnt is a proper word and is a past tense of learn.
Welcome to the ludicrous world of English.
Idiom - throw in