The SP-590UZ has excellent overall performance. Despite the size of the lens it starts up in approximately 1.6 seconds, and even if the lens is fully extended it shuts down again in under two seconds. In single-shot mode at maximum image quality it can maintain a shot every two seconds using a faster H-class xD card, and 2.5 seconds with the slower M-class card. In standard continuous shooting mode it can manage just over a frame a second, although the buffer fills up after seven or eight frames, pausing for several seconds before shooting can resume.
The camera also has two high-speed continuous shooting modes, one of which can shoot at 10fps but is limited to 3MP, the other shooting at 6fps at 5MP. Both can shoot a sequence 25 frames.
The autofocus system is very good. In decent light it focuses very quickly and accurately, and it also works exceptionally well in low light, even when zoomed in, although it is a bit slower. It has a bright and very focused AF lamp with a range of well over four metres, and will focus in darkness even when zoomed in some way, although full zoom does cause some problems here.
The SP-590UZ also scores highly on overall image quality, although it's not without a few issues. The lens has very variable performance. Centre sharpness is good at wider settings, although it does produce quite a lot of barrel distortion, and suffers from significant chromatic aberration and blurring towards the edges. At longer zoom settings the chromatic aberration becomes much worse, and the barrel distortion is replaced with mild pincushion distortion, although the overall sharpness and level of detail is good, at least around the centre of the frame.
Colour rendition is very good, and colours look bright but not garish and retain detail even in saturated areas. Dynamic range is about average for a12MP camera, in other words there's almost no shadow detail, but at least the metering tends to avoid burning out too many highlights. There is a Shadow Adjust function which can be applied in either shooting or playback mode, but it just selectively boosts the ISO in the darker areas, causing image noise problems.
As usual with very small over-crowded sensors image noise is a major issue, with significant noise levels from 200 ISO upward, and fine detail being lost at 400 ISO. If you're not too fussy then 800 ISO is just about usable for small prints and web images. Exposure remains consistent at all settings, but the image quality at higher ISO settings is pretty terrible. 3200 and 6400 ISO are available at 5MP resolution, but are so poor as to be effectively unusable.
I started out not liking the SP-590UZ, and I still think the oversized zoom lens is a big mistake, but I have to admit that the features, handling and performance are excellent, and its superb low-light performance does go some way towards redeeming its disappointing image quality.
The Olympus SP-590UZ has a lot to commend it. The price is good, and the overall design is attractive and functional, with very good handling. It performs well and it's low light performance is especially good. However that title-capturing 26x zoom lens is far too big, produces inferior image quality and cannot be used at full zoom without a tripod. Image noise issues are also a problem.