Physically very similar to its predecessor the D3000, the D3100 is built around a 14.2 megapixel CMOS sensor, bringing not only live view but also Full HD video capture to Nikon's entry-level model. Compared to the D3000 the body gets a slight refresh, gaining an extra button to the left of the screen, a drive mode switch at the base of the mode dial, a sprung lever to engage live view and a direct record movie button. The D3100 has a new 11-point AF system, and Nikon has also added an additional AF-F autofocus mode to allow better focusing in live view and autofocus during video shooting.
The D3100 offers little to complain about in terms of image quality, and its new 14Mp sensor delivers very good results. High ISO performance is substantially improved over the D3000, to the extent that images shot at sensitivities as high as 3200 are eminently usable. There's no doubt that the D3100 is one of the best entry-level SLRs available, offering very good image quality coupled with speedy operation and straightforward handling.