My one works really well, chips area bit like like an armadillo, crunchy on the outside and soft on the inside...
Takes about the same amount of time as doing in the oven (when you include doubling the time), and taste much nicer. Making chips from scratch (no need to boil the potatoes) its about 35-45 minutes, and uses only a little bit of oil, so not too unhealthy.
It also advertises itself as being able to do all sorts of food. I only attempted this once, doing some chicken with various veg, and it worked pretty good too.
If doing chips you can get away with wiping it with kitchen paper to clean it, which is nice and easy.
One issue is it is very loud.
My one is big though (have an XL version), you probably don't want to keep in on the worktop unless you are using it every day, so need space to store it. I do go through stages of not using it, but unlike some kitchen gadgets, its not hidden away for ever and in fact have used it 3 or 4 times this couple of weeks as the wife has been ill in bed so wanted to do hassle free cooking