The only downside for me with cortifoam is that it is a steroid, and that brings with it potential side effects like adrenal supression, weight gain, etc. Worked wonders for my UC though when I needed it. Very convenient to use, just put it in and you're good to go, unlike watery enemas.
I believe there is a mesalamine foam in Europe that is not available in the U.S. which is a shame.