Ultra-modern would really put me off, as it's not easy to put your own stamp on (unless completely ripping it all out, which would seem stupid if it's all new!). I genuinely don't think this 'grey' look is in style anymore - it's more quirky and colourful, or lighter colours.
It's a family house - but the area is likely retirement, and the decor is 'city flat'?
Some nice features (wooden/laminate floor, iron radiators and log burner) but they clash with the grey walls, staircase and carpets.
The kitchen really sticks out as not being done, and would be expensive to do (adding to the list price).
The bathrooms - everything clashes? So much going on here.
The photos are awful. They look warped and make the interior look small and dingy.
Better photos, repaint the walls. New carpets if you can afford it and possibly try to dress the space a bit?
Colourful prints on the walls, some colourful accessories in the bathrooms might make them more trendy, and some plant pots etc.outside wouldn't go amiss!