Like others have said, you can get more gears in a similar style if you want. Hilly terrain may require more gears but a lot of it boils down to riding style. I was on vacation last week near a wilderness area. The only roads were dirt and gravel so I took my mountain bike which isn't my usual ride. I was mildly annoyed by the widely spaced gears (even with 24 speeds), but the range was nice for the hills. So I personally wouldn't care for a three speed even on relatively flat roads just but lots of people like them.