Working with expired film is some of my preferred type of work, however it comes with many risks and great inconsistency. Frequently the biggest risk is whether the film has been stored properly or not. Old film that has been kept in a hot attic, a closet, or anything aside from a freezer regularly yields unusable results, and on the rare occasion it leads to amazing effects.
But what if the film has been stored well? Then it's more likely to behave the way that it should, but there's no guarantee. The biggest risk though is the inconsistency that comes with it. There have been times that I have shot a roll of expired film and it turned out one way, and then the next roll from the same batch will turn out a completely different way (Sensia 100 is a good example of this, as seen below.)
It can be both fun and incredibly frustrating at times. I liken it to spinning a roulette wheel; there’s no anticipating what results you will get. That gamble is something that I greatly enjoy. However, because of its risky nature, I almost never will utilize it for a setting where the results matter or are of importance (such as weddings) and mostly reserve it for my own personal use, fun, or experimentation.