I had been using SBI account since last 5 years and below is my detailed experience about the different facilities
Provided by the bank.
Phone Banking - Phone banking provides ease to use majority of the banking facility, Application is easy to use anyone can understand easily how to operate. No extra charge has to be paid for this service. But this facility has to be initiated by going to home branch.
ATM Service - SBI is best for ATM service as it has maximum availability of ATM.
Internet Banking - SBI internet banking is one of best internet banking facility as compared to other bank. But still for change of mobile number or prfile password you have to visit branch.
Customer Service - This is some thing where SBI has to improve. At branches support is not that much effective. SBI call centre are more of use to get information about any banking facility.
I suggest that call customer care before going to SBI branch, customer care will provide detailed information about documents needed and procedure for any facility/banking