Welll... the skins YES. The seeds, I guess it would depend on the mesh you use. When making tomato sauces, I usually try to use romano tomatos that have very little seeds. Plus I gut them of any visible seeds. When making a tomato sauce, I would simple roast the tomato quaters with evoo, garlic, pepper, basil, and a bit of salt, then let cool and run through the food mill. Such a sweet and flavorful sauce.
I guess my question would be: Can you use this thing for any other application than tomatos. Like Susan said, it could be classified as a unitasker. And if you are not going to be in the business of making tomato sauce, then I could see where this may not get as much use as a food mill. But that being said, I can't boast that I have used my food mill for anything more than making tomato sauce.... so there you go! But at least if I find something else to use my food mill for, I know it will be there for me.
HTH... I'm a rookie!