Is it me, or my 450D? Focussing and image quality

The available light for these photos is amazingly dim. Use the finger wheel to set a 1/60 shutter speed then.

It's a rule from heaven, Ken Rockwell, to use fill flash on photos of persons when outdoors.

Keep an eye on your shutter speed and do not let it get so low as 1/4 unless you want to take chances with an IS lens.