Not good for DSLRs even if "compatible"

I bought the FL-20 to use with both my Olympus E-500 and SP-350. I wanted something that would work with the SP-350 but not be absurdly large on it—as it is a very small camera. Unfortunately the FL-20 is not very useful on the E-500. The problem is that the E-500 uses the camera’s built-in flash to assist auto-focus. But with the FL-20 attached to the camera the built-in flash is down and can no longer assist with focus. The result is a camera that can not focus on indoor pictures. Rather ironic that a flash makes taking pictures more difficult.
I have only tested the FL-20 on the SP-350 very briefly but I did not see a huge improvement in photos with the external flash (vs the onboard). It may help with indoor shots in larger rooms that I was testing it in, but I have to say that my initial impression is one of complete disappointment. Mostly due to the auto-focus issue. Nearly all of Olympus’s DLSR lack an AF assist light on the camera, so this flash is not very useful for them. I would suggest that the FL-20 be used only on non-DSLRs. It’s a shame as the size of this flash is perfect.