Noise

Though the GF1's JPEG images show Panasonic's characteristic blue-channel compression problems--which appear as yellow blotches and streaks--it's far better than I've seen in other models, and doesn't become overt until about ISO 400. (Even if you don't notice it at lower ISO sensitivities, it might become a problem when you start playing with the tonal range. Shoot raw if you plan to retouch.) Color noise appears at ISO 400, with detail smearing becoming a problem by ISO 800. As ever, though, this depends upon your scene content and lighting conditions.