I have been with Zerodha since 2010 and have never had any problems. Great Customer service. The platform is pretty simple wish they had some more features. Love the educational resources - Zconnect.
Any trader looking to save substantially on the trades without sacrificing too much, should absolutely consider Zerodha(Peace of mind). Overall I am happy as Zerodha customer.
Calculate breakeven points using brokerage calculator, Compare using savings calculator, No hidden or extra transaction fees.