A friend of mine is in medical school, and she recently did her surgical rotation. She got to witness an ileostomy reversal, and she said it was pretty interesting. The digestive system is really amazing in that it can still function, even if entire parts of it (like the colon) are missing.
My friend also told me that people have a difficult time with ileostomy related surgeries psychologically. It can be embarrassing to have to run to the bathroom a bunch of times a day or deal with "accidents."