I am using mi note 3 from a while now approx 3 months and can tell that it is the best android mobile phone with 3gb ram and 32gb internal qualcom processor will giv u lag free experience while gaming or with heavy usage of wifi and internet
But faced an issue that the charger provided in isnt that fast and the weight of cell phone is somewhat more( because of huge battery)
I have given it 4 star because sometimes( rarely) faced it thrice in last 3 month that while playing heavy games the mobile just restarts but its ok as when the ram hi full the device has to clear some memory
If you are looking for the best smartphone than after MI note 4 give it a try.
THANKS