We have owned our deep fat fryer for almost five years. When we first bought it, I was terrified that we would just eat fried foods all the time and I would get fat. Luckily, this has not happened yet... but I promise you, if you get one, you won't use is much as you think, and it will change your life in a good way.
There are so many foods you can make using your deep fat fryer. It is easier and less messy (none of those non removable oil splatters on your clothes) than pan frying, plus you can reuse the oil several times (depending on what you are frying).
Things you can fry in your deep fat fryer: corn dogs, fried chicken, hot wings, fried wontons, homemade tortilla chips, fries, taquitos, chimichangas, fried fish or fish sticks, onion rings... or you can get creative like us and do bacon wrapped hot dogs, fried peaches or apples, fried avocado, the possibilities are endless!
Some downsides to a deep fat fryer: it is unhealthy (like that would stop me!), changing the oil is a process, and overall the outside gets a little gross after about five years. However, changing the oil isn't that horrible, though I do put it off for longer than I should.
My dream is to one day have a fryer built into the counter top...