De Havilland Building

They get three stars for leaving me alone most of the time. But they're also incredibly slow to respond to any maintenance requests and don't keep to their appointment times.

If you cannot sterilise the apartment when you leave, they will charge you a straight £150 for "professional cleaning fees" (twice the amount of the market price for the apartment size). One wonders if their in house cleaners are paid all of that money.
I left it better than I found it, yet I still got hit with their fee because the skirting boards had a few scratches and the walls weren't pristine. Probably due to the paint being wafer thin and water soluble but maybe I'm the bad guy there. All surfaces disinfected, carpets cleaned, bathrooms bleached, hoovered and mopped twice etc etc. £150 flat fee.
Want to argue it with pictures? Go for it, they will still say it's £150 because they know that you need the rest of the deposit sooner than they want the deduction.

If you're already a tenant, you should consider that if you're not completely committed to erasing any mark of your presence (yes, fair wear and tear included) with a toothbrush and buckets of paint that you're not allowed to use then just don't bother cleaning it when you leave. Waste of time and effort for something they will charge you for anyway.
When I moved in, I found it in an awful state and had MCR clean it. Now I know why the last tenant left it like that.

Oh my God no. If you have the option, steer clear. If you don't have the option, go for the only block of flats available with electronic locks and a gated car park.