I am an hdfc bank customer for one year. And all I can say is that hdfc bank is one of the best banks from India.
-The phone banking facility is awesome with regards to HDFC bank, HDFC bank app never got crashed.
-The ATM is available all the time, I had faced problem only one time, Considering the ATM booth they are well maintained all over the India.
-Considering about internet banking, it is also good.
-Customer service is also good, they customer service provider are always available and they know how to work efficiently.
So all and all HDFC bank works great for me.
This review is based on my expreience.