The FC100 is all about performance, so it's no surprise that it starts up quickly in a little over two seconds, although it does take three seconds to shut down again. In single-shot mode at maximum image quality is can shoot at approximately one frame per second, and also has a full-resolution continuous shutter mode which can shoot at 1fps until the memory card is full, both of which statistics are suitably impressive.
Casio has always had a good reputation for very fast autofocus systems, and the FC100 can focus almost instantly in a wide range of lighting conditions. It has a good bright AF lamp, and can focus in total darkness at a range of around three metres. The face detection system is also better than average, and can manage to detect, focus on and correctly expose faces in quite low light.
Overall image quality is good, although compared to other £300+ compact cameras it does look a bit weak. The 9.1MP sensor produces image files averaging around 5.5MB, which shows relatively low compression. The lens is good, producing very little wide-angle distortion and virtually no chromatic aberration, with good corner sharpness. Colour reproduction is very good, recording detail even in bright saturated colours, and even dynamic range isn't too bad for a small-sensor 9MP compact, capturing a reasonable balance between highlight and shadow detail.
Unfortunately where it falls down is on image noise, something which has often been a problem for Casio cameras. Image quality at 100 ISO is pretty good, but even here images look over-processed, with artefacts around high-contrast edges, as well as blotchy colour in darker areas. From 200 ISO upward to the maximum 1600 ISO image quality gets progressively worse, with little shadow detail and major noise problems.
The Exilim EX-FC100 is a unique camera, combining a well-made and nicely designed high-performance ultra-compact with HD video capability and some entertaining and potentially useful high-speed shooting and video recording functions. There's no doubt that the 30fps continuous mode could be useful for action photography, but the HS video is a bit of a novelty gimmick with resolution too low to be genuinely useful. It's also a very expensive camera.