I've been playing with the S5700 for a couple of days now and the results are pretty good at the lower zoom ratios - the higher end there's a little purple fringing around areas of high contrast, but you need to look closely to see it. At full 7mp resolution it can take over 1000 pictures on a 2gb SD card! Even so, I'll probably set it to 4 megapixels for routine use, since most pictures will probably end up reduced in size for web pages etc.
Here's a couple of pictures I took today, the usual canal-side ducks, this time in Regents Park. WARNING - VERY large!
Tried to get some photos of coots too, but they were too busy beating up the ducks to cooperate; they really are aggressive little buggers compared to ducks, just wouldn't stay still.