We live in the North, where it is dark, cold and damp for a large proportion of the year - I know that many people have no difficulty hanging out and air-drying to crisp perfection vast quantities of laundry in January, I salute you all, but I am mysteriously incompetent at this feat.
Over the years, we have somehow contrived to live in a series of dwellings that didn't have space for two machines. So we have always had washer-dryers.
They're fine. They wash clothes. They dry clothes.
Unlike a dedicated dryer, they usually can't dry as many clothes as they could wash. You could consider this a terrible flaw.
Mostly we find it quite handy, because often in the laundry basket we have a mixture of tumble-dry-able and non-tumble-dry-able items that we want to wash:
so we chuck the whole load in
wash it using the wash function
when the wash finishes we extract the non-tumble-dry-able items
hang up the non-tumble-dry-able items on drying-rack arrangement of choice (in our case a collapsible rack in the bathroom, with a dehumidifier)
use the dryer function on the tumble-dry-able items
Summary:
whole load laundered
partial load tumble-dried
partial load air-dried, meaning (1) requires smaller drying rack arrangement (2) requires less tedious hanging of clothes on drying rack arrangement (3) generally air-dries quicker than a full load because less moisture in the air.
Result:
whole load clean and dry.
YMMV.