I used my brother's SD500 extensively in May while in Cuba. I have no reason to believe you wouldn't be as happy with the SD400 if resolution isn't high on your list of concerns.

The lens is very good (sharp, decently fast), the processor/firmware very snappy, pictures have superb color and it takes excellent (better than excellent) underwater pictures (this is a good measure of low light and focus performance).

My only wish were that the mode dial and tele/wide controls were swapped. Anyway, he printed about 400 pictures from our trip - and he didn't take that many more while we were away. Goes to show that the vast majority of shots came out quite well.

If you need to take low light shots of distant subjects (too far for the flash), like any camera, use a tripod or other support device. The flash was respectably powerful for a small camera though.

Bruno