It has always been recognised that, even with a good signal strength, some households will have to upgrade their aerials for digital reception. Many people who've been able to get adequate analogue reception, through the type of aerial which you can buy for a fiver on a market stall, will probably find they need to upgrade to a decent aerial, with perhaps 48 or 60 elements.
However, it should be remembered than many areas, which have had the transmitter work completed, won't get a full strength digital signal until the analogue transmissions, for that area, are switched off. (Many digital transmitters are currently running on reduced power, to avoid interference with the analogue signals). So people, who're currently experiencing problems with Freeview, might find that the problems disappear after their local analogue transmitter is switched off.
It's also always been accepted that there are a small number of households which will never be able to receive Freeview. Those homes will require FreeSat, if they don't have a satellite or cable subscription service.
Chris