Body & Design
The D7100 is very similar in size, layout and functionality to the D7000, but now incorporates the operational changes to movie recording and live view activation that have been implemented across Nikon's current generation of enthusiast-oriented DSLRs. As such, both D7000 users looking to upgrade, as well as D600/800 owners looking for a second body will find most of the key controls right where they'd expect them.
There are exceptions, though. D7000 upgraders will have to adjust to the position of the magnification buttons being swapped, with the plus (zoom in) button now being above the minus (zoom out) button. And D800 owners used to a top-mounted ISO button will have to get used to activating that option via a rear button on the D7100, where it is more difficult to find by touch.
The D7100 features a solidly-built magnesium alloy body that offers moisture and dust resistance. The functionality of both front and rear dials can be adjusted via the extensive custom menu options familiar to Nikon DSLR owners. And, like the full frame D600 and D800 models, the camera's mode dial is locked to prevent accidental operation. The ports on the D7100 are arranged behind three hinged doors. The separation means you only have to leave a narrow door open if you choose to attach the WU-1a Wi-Fi module.
A seemingly small feature, but one we're very pleased to see on the D7100, is the ability to customise the rear 'OK' button to be a one-click magnifier in playback mode. This is a huge time-saver that we've come to really appreciate when reviewing images taken with the D800 and D4, yet one that is frustratingly absent from the D600.
Compared to Canon EOS 7D
The Nikon D7100 is the company's flagship APS-C DSLR and thus competes most directly against Canon's admittedly long-in-the-tooth EOS 7D. The D7100 is a decidedly smaller, lighter camera, that offers higher resolution (24MP vs 18MP) but a slower maximum shooting speed.
Compared to Pentax K-5 IIs
The D7100 and the Pentax K-5 IIs are currently the only Bayer-pattern APS-C DSLRs to forgo an anti-aliasing filter. The D7100 has a higher resolution of 24 vs 16MP but both cameras offer weather and dust resistant sealing.