The way you eat will likely change, at least for a while. The first year was a period of adjustment for me. I had to eliminate insoluble fiber, alcohol, tomatoes, and seriously reduce white flour and sugar.
Some centers recommend a Mediterranean diet for j-pouchers. Some suggest a diet high in protein. The advice across the board seems to be to limit too much sugar and foods heavy in processed carbs -- white bread, pasta, etc. I'll be two years from takedown in June and I stick to the Mediterranean diet but limit insoluble fiber.
It is important to have your pouch constructed by a very highly experienced j-pouch surgeon. Otherwise mechanical issues could occur that can impact what you eat. But with a well constructed j-pouch and a little patience, you can probably expect a varied healthy diet.