I am using airtel broadband since 1.5 year and no complaints till now. I stated with 4mbps 15gb plan for 1299 and after completing 1 year they upgraded it to 40gb 8mbps plan for 1399 as I completed 1 year with airtel.:):).
about connectivity and speed: v.good connectivity and currently getting around 900kbps to 1mbps download speed.
about customer service: good customer service as all the issues are resolved in given time.