i don't think it would be wise to outright dismiss the reviews from unhappy staff. while there is always a number of unhappy people in every org, i think the volume of negative feedback is something to take into consideration as well. after all, there is no smoke without fire and not every negative review is because of "misfit" or "personality clashes". this is the sort of perspective that leads to real organisational problems being ignored and swept under the carpet (because the assumption must be staff cannot fit in right? not the org's fault that things are dysfunctional), which then leads to the vicious cycle of staff becoming unhappier and then leading to high turnover. this is not to say your father's anecdotal experience is inaccurate, but it may be that your father is lucky to be in a team that is relatively isolated from these systemic problems, especially in public service where different departments can be very siloed from each other.

end of the day, agree that anyone with an offer should take the reviews with a pinch of salt but still be prudent enough to acknowledge the possible issues. of course, best is to ask someone you know who is working there to know whether there is any truth to the reviews.