Photo.net have published a comparitive test of the $100 Canon EFS 18-55mm, which ships with the Canon EOS 300D digital SLR, and the 12 times more expensive Canon EF 24-70mm L series lens.

“Despite the fact that the “L” lens won in every comparison, I’m being pretty picky and I’m looking hard for faults. The EFS 18-55/3.5-5.6 actually looks like a pretty decent lens for casual use, and at $100 it’s probably a bargin. It seems to suffer from the same defects that I’ve seen in similar low end, plastic mount, canon lenses (22-55/4-5.6 and 28-90/4-5.6, both of which sell for around $100 also). Contrast tends to be low, especially wide open, and edges tend to be soft. If you’re intending to shoot landscapes and make full frame 13x19 prints, you’re probably going to be disappointed. On the other hand if you’re printing 4x6 prints you’ll probably be delighted. At 8x12 it probably depends on how picky you are.”

Website: Canon EFS 18-55mm vs Canon EF 24-70mm L Lens Comparison