I have been using Microsoft Lumia 640XL from last 10 months, and having excellent experience with it.
Display is made of strong, scratch-proof gorilla glass, but once it dropped from just about 2 feet and it broke. So, can’t suggest based on gorilla glass apart from that screen quality is sharp and very good.
Sound quality is moderately high and clear for both, Caller voice and Ringtones.
I found best camera in this class, as it produce very sharp and clear image. still images also capture images in video form of 1 second, sounds pretty.:) Even manual mode is available which is best in its segment.
When it comes to battery performance, its excellent because of its 3000 mah battery. It easily runs for whole day and more, with regular use. it has battery sense which help to increase battery performance.
Heating is not an issue with this mobile.
provided earphone quality is not very good, even it does’t support OTG.
Even multitasking is not so smooth as you can do in android mobiles. furthermore, some apps get crashed few times.