manual treadmills - are they worth it?

i want to get a manual treadmill that i can use to walk on during the
winter months. i have seen mixed reviews online. some magazines say
that none of them are worth it, and others are fairly neutral about
them. does anyone own one that they are happy with? i have been
searching around for used ones and two people responded to my ad - one
lady has an easywalk manual treadmill by rock fitness, and someone else
has the one that they sell at target. i think it is a fitness quest, or
something like that. any opinions from folks who have manual treadmills
and use them regularly would be greatly appreciated!