There are very few reason not to buy this phone. First of all processor, processor is very important for the phone but the processor which is providing in this phone is not good if we compare this to other phone like xiaomi. K5 note is not for the gamer it is pretty good for normal gaming but it is not good for the high graphics game so any one who is game addict the phone is not good for him/her.
This two are main drawback now we can talk about some other reason like display, there are some people who preffer smaller screen. There are no dedicated sd card support. Battery is smaller if we compare with xiaomi they are providing 4000 mah battery at the same price. The speaker is on the back side so I am personally missing the front firing speaker. These are some reason why not to buy the phone.