The X90's overall performance is pretty good for a superzoom camera. It starts up and is ready to shoot in just under three seconds, and in single-shot mode it has a shot-to-shot time of also just under three seconds, which isn't exactly sparkling performance but is a full second faster than the X70. In continuous shooting mode it can maintain approximately 1.25fps, which is actually pretty quick for a 12MP camera. It also has three burst modes of varying speeds, but since there is no audio cue to let you know when a picture is taken, and the monitor remains blank, these aren't really much use.
The autofocus system also seems to have had a bit of attention during the upgrade process. It is still very accurate and reliable, and even works well in low light, but it is now much quicker, focusing in a fraction of a second. This is a big improvement, and significant boost to the X90's performance.
Also vastly improved is the camera's battery duration. The 1250mAh Li-ion cell powering the X90 is over 25 percent higher capacity than the battery in the X70, and as a result it can keep shooting a lot longer. I was able to shoot around 220 shots before the battery indicator dropped to one bar and turned yellow, indicating that it needed a recharge. It kept shooting though, managing 270 shots before it finally ran out, exceeding the manufacturer's claimed 255 shots.
There have been a few changes to image quality too, but the X90 still has some room for improvement in this area. The X90 has a new lower sensitivity setting of 80 ISO and appears to have a new noise reduction system. At lower sensitivities the image quality is generally good with no visible noise, but the results tend to look a bit over-processed. By 400 ISO the noise reduction is blurring out fine detail, and at 800 and 1600 ISO noise is a real problem. 3200 and 6400 ISO are available but only at 5MP resolution.
The new lens however is excellent. Pentax optics have a very good reputation and despite its gigantic zoom range the X90's lens produces superb edge-to-edge sharpness with no trace of chromatic aberration or barrel distortion. This may be due to corrections at the processing stage, but the results are still impressive. Colour rendition and dynamic range are better than average, and exposure metering and focusing are reliably accurate. All in all a significant improvement, and hopefully a sign of great things to come from the Pentax X range.
Although it is only a relatively minor upgrade over the X70, it's enough to put the Pentax X90 into the top bracket of superzoom cameras. Build quality, design and handling are right up there with the best, and the improved performance and battery duration are very welcome. There's still room for further improvement in image quality, but the results are far from disappointing.