Sorry I haven't read all 16 pages but looking at the video tour, the first thing you see as you enter is the downstairs loo which is very tired. Looks like a mismatched coloured loo and white toilet seat? At least find a matching seat, or replace the loo which really wouldn't cost much. I would change the flooring too, an offcut of vinyl or even self adhesive tiles would cost very little and brighten it up a lot.
There are quite a few marks on the walls. Hard to tell from the photos but a magic eraser might get a lot of these off and make it look a lot cleaner without the need to paint. But generally it just all looks unloved and not like a home that anyone cares about.
Things that would put me personally off but other people might be less bothered about:
I have a real dislike of a living room that's essentially a corridor to other rooms. I don't want to have to walk through the living room to get to the kitchen. Definitely a personal thing but I've turned down houses for this reason.
The kitchen would be too small for me. The living room also looks small for the size of the house, especially if other rooms lead off it.
Bedroom 4 is not a bedroom.
The round thing in the garden is weird. Is it a patio or a pond cover or what? If it's a patio, put furniture on it so people can tell it's a patio and not a manhole.
Agree the exterior shots make the estate look very cramped. I'd remove them completely.
The panel thing in the loft would bother me. It looks ugly and unfinished.