Like any other smartphones there are always some pros n cons. Even the flagships from.Samsung, HTC or Balckberry are gonna have some of them.
I received this phone few days back . its a good phone but not the best
Pros
CPU is 1.4 GHz Snapdragon 430 which is a 64-bit octa-core chipset.
Coupled with of 3 GB of RAM for multitasking.
For gaming it comes with a GPU of Adreno 505.
Very fast 13 megapixel primary camera.
Next Xiaomi Redmi 3S advantages or pros is the massive 4100 mAh battery.
Operating system is the latest version of Android Marshmallow.
Comes with 32 GB of internal memory.
External memory is expandable up to 128 GB.
The body is made of metal on the back and plastic on the front.
It has got a fast charging technology for the battery.
USB OTG cable is supported which is another advantages.
The user interface MIUI is very pleasant and enjoyable to use. It smooth like an iOS.
IR blaster is present for remote control of home electronic appliances.
Cons
It is not a full HD screen. It has a resolution of 1280×720 pixels with a pixels density of only 294 ppi. Today you can get a full HD screen smartphone than lower the price of this one.
Second Xiaomi Redmi 3S downsides or disadvantages is that using two SIM card is impossible if you insert a memory card as the slot is a hybrid design.
The small f/2.2 focal aperture of the selfie camera produces grainy pictures in low light conditions.
Limited numbers of service centers is another Xiaomi Redmi 3S Prime disadvantages or drawbacks.
It does not have Gorilla Glass protection for the display.
The buttons below the display are not backlit.
And finally the last cons or disadvantages is the battery which is non user replaceable as the back cover is non removable.
Over all its a decent phone in a price range of 8999