The A3100's overall performance is pretty good. The camera can start up and take a picture in well under three seconds, which is quite quick, and the consistent shot-to-shot time of approximately 2.2 seconds is also respectable. In continuous shooting mode it can maintain approximately one frame a second apparently indefinitely, which is pretty good for a what is after all a relatively cheap camera.
The autofocus system is very good by most standards, but is slightly let down by the rather clunky focusing motor in the lens. Nonetheless it focuses quickly and reliably in almost any lighting conditions, with a good bright AF assist lamp giving it a range of around four metres even in total darkness.
Unusually for a Canon camera, the A3100's only real weak spot is its image quality, which has a number of annoying problems. The automatic white balance is unreliable, causing colour tints when presented with large areas of green in an image, obviously something of a disadvantage for landscape photography. The lens too is far from perfect, with with significant barrel distortion at wide angle. Overall sharpness is good, but there is a lot of chromatic aberration towards the corners of the frame.
The biggest weakness however is noise control, which is usually a strong point for Canon cameras. Images show significant colour and luminance noise at 200 ISO, and while the noise control does clean things up a bit at 400 ISO it only does so at considerable cost in fine detail, which gets worse at 800 ISO. The quality at the 1600 ISO maximum is very poor indeed. All in all a bit of a disappointment for what was looking like a pretty decent little compact.
The Canon PowerShot A3100 may not have the creative versatility of its forebears, but it is a well-made and sensibly designed camera offering a useful specification at a reasonable price. Build quality, handling and performance are all up to Canon's usual standard, but unfortunately the camera is let down by inferior picture quality.