Not surprisingly, the S5800's overall performance is almost identical to the S5700. It starts up in a bit over two seconds, which is very quick for a super-zoom camera, but then the lens is non-extending, which makes it quicker. It shuts down again even more quickly, in about half a second. Shooting time is a fraction slower than the S5700, with a shot-to-shot cycle time at the highest quality setting of approximately 2.7 seconds. This is a bit slow, and I had assumed that it would be because the larger sensor was generating correspondingly larger file sizes, but in fact the S5800 generates significantly smaller JPEG files than the S5700. The average file size for the earlier camera was approximately 2.8MB; for the S5800 it is only around 2.6MB.
There was another surprise in store, which is that the overall image quality produced by the S5800 shows no detectable improvement over the S5700. Yes, the images are slightly larger, but the level of visible detail is no greater. The same is true of the high-ISO noise performance. I could detect no difference in the level of image noise between the two models. Both perform about as well as a good compact camera of similar resolution, producing good image quality up to 200 ISO, but getting progressively worse from 400 to 1600 ISO as the rather savage noise reduction reduces sharpness and detail. The lens performs fairly well however, with excellent centre sharpness at all focal lengths, and only showing significant corner blurring and barrel distortion at the very widest setting.
Like the S5700 before it, the FinePix S5800 offers more photographic control than anything else at the price. Excellent ergonomics, good build quality and good performance belie its low cost. It would make an ideal camera for anyone on a tight budget who wants to learn more about creative photography. The lack of image stabilisation is a disadvantage, but not a crippling one, however it's definitely not worth binning your S5700 to upgrade.