My husband surprised me with one at Christmas last year. He wanted one, lol.
No, the food does not taste like traditional fried food. It's like the cauliflower pizza crust/bread sticks. It's not bad, but it's not the "real" thing.
Sorry, we've never tried to do doughnuts, so I can't say how they taste. There are lots of recipes for them on Pinterest.
I assume that they come in different sizes. Ours seems pretty big to me - it takes up a LOT of room. Just measured it - 15" high, 15" deep (front to back) and 12" deep.
I'd see if any friends have one that you might borrow, or bring ingredients to use in making something at their home. Personally, I don't like it and, had I spent the $ on it, would be disappointed. But DH bought it, and he likes it. It gets used once a month or so for french fries (I really don't like them) or wings (pretty good, but I think that regardless of how they are cooked, they are fairly unhealthy). I do like oven fried potatoes and oven fried chicken, so would rather go that way than have a little-used, cupboard hogging appliance.