First and foremost, the stand out feature that the Nexus 7 has going for it, is its OS: Jelly Bean. Google made the decision to debut the latest version of their mobile OS, Android 4.1, on the Nexus 7 because of their collaboration with ASUS on the slate.
Jelly Bean is beautiful, and it truly deserves its own review. What makes it stand out even more, is that it is a "pure Android" experience, as it's a purely stock Android OS. This is free of carrier modifications, or manufacturer UIs (skins such as TouchWiz from Samsung, or HTC's Sense). This is a pretty big deal considering the Nexus 7 is one of the most talked about tablets of 2012.
Another bonus ASUS and Google have thrown in with the Nexus 7 is that Nexus devices are sold with an unlockable bootloader, meaning users can root the device for example, without many issues.
Jelly Bean includes Google's "Project Butter", which is an initiative of Google to reduce latency in the OS. Google used "vsync timing" and triple buffering, improving touch responsiveness, as well as programming the display to run at a gorgeously smooth 60 frames per second. This can be felt on the device right away, when sliding between screens and going in between apps, it really does feel like butter.
Also included with Jelly Bean is Google Now, which is a Siri-like intelligent personal assistant. Google's Now service provides "cards", which are forms of information on various topics. Google Now will display these cards when its thinks it's a relevant time to do so, and will display information such as weather, traffic conditions and sports results. Google Now can be accessed by pressing and holding down on the home button on the screen, and dragging out of the circle displayed.
Google Now will learn who you are, and what you do over time, and display relative information that you would personally like to see. The longer you use the Nexus 7 (or any other Jelly Bean-powered Android device), the more personal Google Now becomes. If you were to search for your favorite football teams scores manually frequently, this is the type of information Google Now would pull down automatically for you.
Jelly Bean also introduces Google's Chrome web browser as its new stock browser, finally. After personally using Chrome for Android on my ICS-based Galaxy S II, it feels like such a letdown to use anything but Chrome. Thankfully, Google baked Chrome into Jelly Bean, meaning you can now sync your desktop version of Chrome to your Jelly Bean-powered device, and enjoy your bookmarks, saved passwords and more. It's also quite snappy compared to the usual stock browsers on other Android devices.
There is one thing that I don't quite understand, is that there is no camera app included on the Nexus 7. Sure, the Nexus 7 doesn't feature a rear-facing camera, but there is still a front-facing camera. Surely the base code to Jelly Bean would have a camera app, meaning ASUS have decided to leave it out. It's not a show-stopper, but it makes you question the decision to leave it out. I guess most people wouldn't run around taking pictures of themselves as much as taking pictures, or videos, of other things, but the option of the camera app on the Nexus 7 would've been nice.
There is a camera application that MoDaCo has put onto the Play Store, which isn't a killer app by any means, but it will give you access to the front-facing camera. I've taken some video and photos with it, so you can get an idea of the quality. I will note that it is really hard to take photos and videos with a front-facing camera, as you can't see what you're recording.
Another thing you'll notice on the Nexus 7 is that the home screen is locked into portrait mode. There is no option to change this without looking into third-party tools, or rooting the device. As a stock Nexus 7, it is completely locked down. Applications, including Google's own apps, are able to rotate into landscape mode, but once you go back to the home screen, it'll flip back to portrait mode. This isn't a big problem, but it is something worth noting. I would say that ASUS and Google made the executive decision based on its 7-inch size, but again, why not offer it as an option somewhere?