Nikon is aiming the D5100 at relatively novice photographers who want to take their hobby more seriously and want a versatile camera that will enable them to take more creative images.
The Nikon D5100 is a great choice for these users, but it is worthy of consideration by more experienced photographers as well. There's plenty of control available over the appearance of images and the 16.2MP sensor is a higher performer in average low lighting conditions.
Having a high resolution articulated LCD screen is a bonus, because it actively encourages shooting from unusual angles, which makes for more interesting pictures. Those who rubbish the idea of such a device on a DSLR should try using one for a few hours while taking macro or still life images.
Although the Special Effects are fun, and in some cases very effective, it's a shame that you don't have the opportunity to take some control over the exposure or record simultaneous raw files without the effects.
The only real downside for enthusiast photographers is that there are few direct controls over image parameters. However, most features such as the white balance, drive mode and sensitivity settings are just a couple of clicks away via the Information Display system.
Great for both enthusiasts and novices looking to take the next step forward, the Nikon D5100 offers a lot of versatility, opportunity for creativity and quality results. However, the bar appears to have been raised by the Canon 650D which has a touch-sensitive articulated screen, 18-million effective pixels and a new hybrid AF system that enables faster focusing in Live View and Video mode.