First best thing to talk about redmi 3s or 3s prime is its long lasting battery.Its 4000mah battery makes it to perform humongous tasks for very long time.
Secind best feature is it multitasking ability .more than any smart phone under 10000rs this particular phone provides you with the multi tasking experience inclidi 3gb and2gb ram respectively.
Next good feature of this mobile is its small screen of 5inches display which makes it handy and it fits great in our hand.
And its metal body makes this phone look so slim and stylish.and there lot more feature we make us fall in love with this very great phone.
Coming to disadvantages
1.its 13rear camera which works good during day time but not appreciable during low light.
2.On using for long time in a day it gets heated up a bit this aspect is quite common for xiomi phones.I hope they fix this issue.
At last the conclusion is
If you are looking for smart phone with the best features under price 10000rs then this should be your first choice as per my view.