Raw XML or a nicer view?
Although a raw XML is bad, so is nicer view that doesn't include multiple options to subscribe including at least one email option.
RSS and Atom?
Both is bad and Atom is worse. RSS is supported by every RSS aggregator and Atom by some, not all.
Will users be able to see the pattern in your url feeds?
Unless your target audience cares, this is geek speak for not important to anyone but geeks.
Will you allow your internal users to create (and publish) custom feeds?
More unimportant geek stuff.
Today, while editing Wikipedia, I was messaged that a bot had removed my link to a blogspot blog post. WTF? You can't link to a blogspot webpage anymore? Wikipedia gets more stupid by the day.