Key Differences between all three cameras - If a camera is not listed with a feature bullet it does not offer that feature.

• 24MP with a new sensor(not the same as the 24MP sensor in the D3200 or the D5200) and the AntiAliasing filter has been removed potentially increasing the image quality in some situations.
• D7100 offers a 1.3x crop mode. You resolution is now limited to 15MP but provides additional benefits (see next two bullets)
• 51 AF points and when you shoot in the 1.3x crop mode nearly 100% of frame is covered by AF. D7000 and D5200 offer 39 AF points.
• 6 frames per second, 7 when you shoot in the 1.3x crop mode. D7000 offers 6FPS and D5200 offers 5fps.
• Improved weather sealing - moisture and dust seals.  D7000 was a little less weather sealed.
• D7100 and D5200 share video features 1080i at 60fps with a host of additional resolutions/FPS, D7000 was limited to 1080p at 24fps(which isn't a terrible limit)
• D7100 and D5200 offer onboard stereo mic. D7100 also has a headphone jack.  D7000 offers mono mic and mic jack.
• D7100 offers spot WB
• D7100 and D5200 offer in camera HDR and Multi exposure.
• D7100 and D5200 are compatible with the little WU-1A wi-fi adapter- paired with the Nikon app on a smartphone you can trigger the shutter and download photos.

 Buy the D7100 from Amazon | B&H ( I suspect that this camera will see very well early on and it may be a bit harder to get one at release, the D7000 was well loved) D7100 Sample Images | SD Cards tested in D7100 Should you upgrade?The D7100 is now Nikon's flagship DX model and the image quality out of this camera reflect this level of performance.  I mean simply that this is one of the highest quality crop sensors in one of the best bodies you can buy at this price level and even higher.  If you have a Nikon D5100 or lower model this would be a worthy upgrade.  If you have a D7000, still a very nice camera, it becomes less clear if you should upgrade.  The sensor is better, you have some nice additional features and more robust options in video mode BUT you are likely to see a greater, more long-term improvement investing in glass. A possible exception, if you are getting paid to shoot, especially in lower light environments or situations where you need that full AF coverage (sports and wildlife photographers I am talking to you) and you have somewhat decent lenses already - you should consider upgrading. If you any questions about the D7100, D5200 or other cameras or lenses leave a comment or send me a message on my Facebook page.   Thanks for reading.