As mentioned earlier, there's just one back-facing 5-megapixel camera, when most phones today have front and rear cameras with at least one rated at above 9 megapixels. (A high-end phone such as the LG G3 boasts two cameras with a 13-megapixel rear camera.) There's also the ability to shoot video at 720p and 30 frames per second, which offers capable video capture, especially for snippets going to the Web.
One of the most mind-boggling problems of having one camera only in the rear is that it hinders the ability to take good selfies or conduct a videoconference. Nokia has substituted something called Glam Me (yes, really!), which requires you to hold up the phone while facing its blank rear side while looking into the camera lens, then listen for a series of beeps that increase in tempo to indicate whether your face is centered in the frame before hearing a shutter sound.
Clearly, having just one camera helps Nokia lower costs. However, the fault in this Glam Me system is that while your head (or heads, depending on how many people you're photographing) will be centered in the frame, you don't have the level of control you need over many factors, including facial expression or the proper lower or higher camera angle. There are some editing capabilities in the Lumia 635 that can help correct some problems in a selfie image, but not whether the subject is posed to look completely ready for the shutter click. All those Lumia 635 editing tricks can't make up for the lack of a front-facing camera.
There's one speaker on the rear of the Lumia 635 (unlike the stereo speakers in some other smartphones), which worked quite well when laid on a table to play rock and pop music, but not for orchestral sounds, including strings. I got better sound with ear buds plugged into the 3.5mm jack on the top edge.
When I used the Lumia 635 as a phone, my callers sounded a bit like they were coming from inside a box, but the sound was still clear enough to be passably good.
The power button and volume up and down buttons are on the right side, but seemed a little hard to push sometimes. A standard micro-USB charging port is on the bottom edge.
When I first got my review unit, it wouldn't power down properly. I followed the shutdown prompts, but the phone would at first shut down and then immediately start up again. That kind of start-up after powering down happened at least 10 times, both while the phone was plugged in for charging and while unplugged. After a reboot (accomplished by holding down the power button and the lower volume button for several seconds), that problem corrected itself.
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