Lumia 640 is an excellent phone made by lumia.I bought this phone from snapdeal for 15999 rs and I am fully satisfied with this phone the best features of this phone are
1) The battery life of the phone is excellent battery life.
2) The phone is made with high quality materials and it feels super good in hands.
3) The processor feels butter smooth.I never experienced any lag or hanging up.
4) 1gb RAM might sounds not enough to you but windows manages this memory very effectively.
5) Camera is excellent video quality outperform photo quality.1080p video capturing is very good.
6) Screen is also pretty good, the 294 p display is very good for watching movies.
The problem with this phone are
The front camera is very bad it looks like someone else .9 mp camera doesn’t live up.
The low light performance of the the camera is very bad.
and the problem of less no of application for windows is also a problem.