I do have a Digiflash and I think its great. Still, at about 3-4 EV (400+ ASA) it is pretty much useless when you want to measure the main subject carefully... or maybe not useless, but it does not really help much at all. All it tells you is "expose as much as you can" 😉.
The case is this especially with color negative film, which benefits or at least somewhat perfectly tolerates one or two stops overexposure, while it does not like underexposure. Color negs will be a drag to get right when they are not exposed enough, but "over"exposed ones come out just fine.