If we talk about mobile under 7k redmi 3s is the device which fullfils all the requirements of a basic handset in a budget .
Baterry backup is great and it last full day on heavy 4g usage
Camera is amazing in day light conditions and selfie cam is also very impressive
Look and feel is premium and its too handy to use
Calls are much loud even in trafic conditions
Screen has great viewing angles and pretty much brighter under sunlight
Sound speaker is average but has good sound quality
Phone looks better in Dark grey colour as the front is fully black
It has IR blaster sensor which is very useful in day today life and its compitable with every remote appliance which is a plus point for this device .
Go for it !