I too am very surprised by all the negative comments. Most of these people are leaving reviews for effectively their bad landlords - not Fineholm specifically.
I am a landlord myself and I can assure you Fineholm are very prompt in communicating tenant issues to me, and facilitating their resolution. Given that I live in the USA and rent my flat in Glasgow, it gives me confidence having Fineholm in the middle.
Pay little attention to the rants of a few understandably disgruntled tenants who have bad landlords. What else would you expect on a reviews site? So do you think it's likely that any significant number of satisfied tenants would even bother to leave a review of their letting agency? I don't. And Fineholm facilitates (I'm guessing) hundreds of rentals via hundreds of landlords.
Just my 2 cents