Greatly improves indoor flash pictures.
If you're serious about getting good indoor flash pictures, then something like the DF200 is a must.Use it to *properly* light up subjects at medium to longer distances (something dinky built-in flashes don't have the power for) or use bounce flash at closer distances. I absolutely love how bounced flash evenly lights the people in my photos. You can also turn down the ISO setting, allowing for less grainy photos.The hold button is handy when there are other cameras around you snapping away, but I do wish it was in the form of a switch, which would have been more durable then the small springy button it is currently. Also, the battery door can be a little bit difficult to open and close.Edit: By the way, it works perfectly fine on my Rebel XT/350D & Powershot A70