Got my 830 from AT&T on 11/7. Here is my 2-1/2 day review. For context, I had a 900, broke the screen, got a 520, upgraded to a 1520 for a weekend before deciding it was too big, switched out for an LG Vigor (mid-range 5-inch), hated Android, went back the 520, and now have the 830. And my wife has a new iPhone 6.
The body of the 830 is fantastic. I would have preferred the silver frame, but I have to admit that the dark one looks nice. It's kind of like the stuff they made the first-gen Surface out of. It's very classy. Also, the thickness and the weight are much better than the Icon/930. It's really just the right size.
I'm using the green back. I know that there have been some questions about exactly what color of green it is; I can tell you it is the same eye-searing radioactive green that my 1520 was. Which I like.
I like having dedicated navigation and camera buttons. They look nicer, are better placed, and are easier to use. However, the navigation buttons are finicky about lighting up. Sometimes they do, sometimes they don't. This is more odd than annoying, but it makes me think that Denim and/or the firmware might not be completely baked yet.
The screen looks great. Natural colors, deep blacks, and super smooth. The resolution is good enough that I can't tell the difference between the 830 and 1520. Yes, I know the 1520 has more pixels, but a 5-inch 720p screen looks about the same as a 6-inch 1080p screen from where I'm sitting.
The screen is responsive without tripping over itself. Where the 1520 felt twitchy, the 830 feels creamy. The on-screen keyboard is a joy to use, and is the perfect size for my moderately fat fingers.
Performance is good, but not as immediate as the 1520. I've seen "Resuming . . . " a couple of times but never for very long. I don't play games, so I can't comment on gaming performance, but all of the apps pop right up, and embedded videos play smoothly regardless of their source. I no longer feel like a second-class citizen when I find a Youtube clip on a webpage. Also, unlike on the 520, I'm no longer using a long press on the back key to constantly monitor which apps are running. I just let them run naked and free without a care in the world. Cortana is much faster on the 830 than the 520.
Battery life is decent, but not fantastic. I let screen brightness auto-adjust, and I have used the batter saver app to reduce the number of apps that can suck down juice in the background to less than 10. With those settings and moderately heavy use, I can get through the day on a charge, but not much more than that. If you want a battery that lasts for days, get a 1520.
I haven't used the wireless charging yet because I don't have a charger (Santa, are you listening? I've been good), so I can't comment on that aspect of the 830. I can say that while I initially though it would be weird to have the charging port on top, it now feels perfectly normal. It's kid of like the toilet paper roll: It works just as well on the top or the bottom, but some people have strong enough preferences that there will always be an argument about it.
Bearing in mind that i don't know anything about photography, I'll say that the camera is good, but some photos have come out a little bit noisy. It's still better than the LG Vigor, but not as good as as the 1520. All of my favorite camera tools are on the phone, which is namely the auto-fix and filters form Nokia creative studio. One day I will learn more about waht all of those other buttons do. That day is not imminent.
Reception is great. Wi-fi has the best range of any device in the house, connects quickly, and remembers all of the passwords without issue. I've been really impressed with cellular reception. It's the best of any phone I've ever owned, and it's been tested at the in-laws' not-quite-in-AT&T's-range house in the hills. Phone calls are clear and crisp, and the LTE is speedy and reliable.
Sound quality is good. The sound through headphones is warmer and richer than the 520, and the speaker is plenty loud.
The motion tracker does a good job counting steps, but I haven't been motivated enough to actually do any exercise with it yet. I haven't used the Fitbit Flex that came with it, so I'm not sure how well it works. We may strap it on to the four-year-old and see what kind of data we get. I'm pretty sure he gets at least 10,000 steps a day.
I bought the Incipio Transparent case, which is a soft silicone-style case that was easy to get on and provides excellent protection for both the screen and the small camera hump on the back. It is not, however, actually transparent. It's black, though it shows a little radioactive green around the camera and the speaker. I like it. The buttons are very easy to use with the case on, with no hard pressing required.
So is it an affordable flagship? Yes, though "Affordable" would have been easier to justify at $400 or less. It may not be the best at everything, but it does everything well and looks great doing it. What makes me really happy is all of the extras: integrated wireless charging, a removable battery, switchable back plates, and expandable storage. Compared to the iPhone, it's not quite as smooth (get rid of the "Resuming . . . " once and for all, MS), but it's every bit as premium in build quality, and it has extras that you can't get on the Apple. If they were the same price, I'd chose the 830. the fact that it's $200 cheaper makes it even better. And compared to Android (even a pretty nice mid-ranger like the Vigor), it's a much better choice. If you absolutely have to have the best photos or battery life, get the 1520 and learn to live with the size. If you absolutely want the most kick-*** processor, get the Icon/930 or the HTC One. But if you want something that works well for everything and is easy on the eyes, wallet, and your pockets, the 830 is the best phone on market right now.