Microsoft Lumia 640 is a great phone. One of my favorites. Got one back in March 19 and then sold the other four. I made a tidy profit of 20K PHP after spending 6K for them. So I made close to $400 net profit from it since they cost about $180 EACH where I live. I love it because the camera, loud speaker, clear reception, long battery, and making money out of it is the icing on the cake.
Most of the positives come from the Nokian hardware. It surprisingly takes excellent photos although the flash isn't very strong. It records better videos than my other Androids that cost more. My female cousin who also had an iPhone 4s bought a Lumia 640 from me and said the cam is fantastic for the price. We compared it with her brother's iPhone 5 and the Lumia might be slightly better. In between iPhone 5 and 5s quality. Recording sound is also loud.
Drawbacks? Lack of apps and ones with lesser quality. Facebook Messenger has no video option as told by one of my friends I sold it to. Viber, MX Player, and Netflix are also much better on Android than on WP. Which is why I swapped micro-sd and put the 64gb onto the Moto E 4G. I like listening to the audio of movies or any video sometimes while the screen is off.
Again, if you aren't much an apps user, you will end up loving it. The only flaws come usually from the OS. Nokian hardware is fantastic on it. Everytime I speak on it, I feel like I am on a landline and where I live have dead spots. Hard to get the best signal here but the 640 always comes off louder and clearer than my other phones. This is why I hope Nokia builds an Android equivalent of the Lumia 640.
So for camera and phone, Lumia 640. For multimedia playback, I go to the Android. The Lumia 640 will be a nice edition to your collection and you don't have much to lose for only $29.99 if it turns out to be disappointing. With a Snapdragon 400 and 1GB RAM, it still feels smooth. And added longevity with removable battery and micro-sd slot. WP does eat up your sd card more than Android for some reason. I tried putting exactly the same files on my LG and Lumia, and the Lumia had 1.6GB less.
Just remember to go through your keyboard settings and turn off the gesture swiping . It might lag on you or you experience ghost inputs when nothing is typed for 30 seconds. Double tap to wake screen is there as well as double tap the navigation bar on the bottom to turn off. Browsing also isn't my favorite on WP. UC Browser is my favorite browser on it but I still prefer browsing on Android.
I give Lumia 640 9/10 for its Nokian hardware and 7.5/10 for its Microsoft software. I also had a 635 before which I enjoyed for its long battery life and this one is definitely better with its 1GB RAM, superior camera, and HD display. It is definitely an upgrade from iPhone 4s when it comes to hardware and don't let that $29.99 price fool you that it isn't. I tried many iPhones before and sold them. This 2015 WP budget $30 phone is on par with iPhone 5 and 5c and superior and inferior to them in a couple areas.