The S12's overall performance is, to be honest, a bit average. It starts up in about two and half seconds, which is quick enough, but the shot-to-shot time in basic single-shot mode is a little over three seconds, which is pretty slow by recent standards, and slower still if the "Make up" or extra lighting features are used. The camera has four continuous shooting modes; 20 shots at 10fps and one megapixel resolution, eight shots at 4fps and two megapixels, a 3-shot burst at 3fps and 2mp, but with flash on every shot, and a standard full-res long-period continuous shooting mode, although this is very slow at about two seconds per shot.
As is usually the case with Casio cameras, the EX-S12 has an exceptionally fast and accurate autofocus system, and works well in low light thanks to a good AF assist lamp. The flash is also surprisingly powerful for its size, with a range of at least four meters and excellent frame coverage.
Image quality, and particularly image noise, has traditionally been a weak point for Casio compacts, but the EX-S12 shows encouraging improvements in this direction. Images are largely noise-free at 400 ISO, and have good detail and colour rendition. Even at 800 ISO image quality is far from unusable, although the effects of the noise reduction system are clearly visible.
The only real weak point is the lens, which isn't particularly sharp even in the centre of the frame, and suffers from blurring and chromatic aberration at the edges of the frame. It also suffers from very obvious barrel distortion at wide angle. Casio used to fit canon lenses to its better cameras. Maybe it would be wise to do so again.
The Casio Exilim EX-S12 is about as small and light as an ultra-compact can get without being too fiddly to use, but nonetheless packs in an impressive list of features and an easy-to-use interface. Overall performance is a little slow, but the excellent autofocus and good low-light capability, combined with some fun options make this an ideal camera for social and holiday snaps.