Review: Nokia Lumia 820 for AT&T
The 820's display measures 4.3 inches across the diagonal and has 800 x 480 pixels. This stops well short of the higher-resolution displays on the 920 and HTC 8X, (also sold by AT&T,) but it still manages to look good. It’s very bright and colorful, and all the on-screen elements are easy to read and see. You will notice individual pixels only if you hold it close to your eyes. As with other Lumia devices, the 820's display was easy to see and read outdoors.
The 820 did well on AT&T's HSPA+ and LTE networks. It never had any trouble connecting to AT&T's voice and data networks no matter where I took it. In areas with LTE coverage, it was quick to connect to LTE. It also transitioned from LTE to HSPA+ smoothly. Calls always went through on the first attempt, and the device didn't drop any calls during my tests. Data speeds were mostly excellent under LTE and very good under HSPA+.
The quality of phone calls made with the 820 were good. They free of background noise and interference, and the earpiece produces clear sound. I was slightly disappointed with the volume produced by the earpiece, though. It's fine for use around the house, but outdoors or anywhere there's a reasonable amount of noise and it will be hard (but not impossible) to hear. The speakerphone offers the same call quality and better volume than the earpiece. Ringers and alerts make plenty of noise to get your attention, and the vibrate alert is quite strong.
The 820 didn't provide quite as much battery life as other Lumia devices, like the 920 or 810. It lasted a full day, but barely. I found it lost almost 50% of its charge just sitting overnight. When unplugged at 7AM and used lightly throughout the day, it was gasping for breath at 11PM. Using it heavily drained the battery by 8PM or 9PM. You'll definitely need to charge the 820 every night, and keep a charger handy just in case.