It’s a killer phone .I am using it for 5 months and itbworks good and has no problem like heating, lagging, etc. So you can go for it without any thinking, I thinks that it is best phone under 10 k . So buy it from flipkart because it gives you highest discount than other shopping sites.
Its is now upgradable to android marshmallow( 6.00v)
If you want to buy other than k3 note you can go for the followings-
1.Radmi note 3
2.Moto G 3rd
3.Moto X Turbo