When the service is from Airtel then absolutely don’t worry much about the speed and coverage. Airtel provides better speed and coverage as compared to any other service provider in India. You will find the coverage of Airtel as the best among all the service providers in India.
But as a word of caution, please discuss the speed of the Airtel Data Card with the retailer in your area because it sometimes happens that you will be getting a good coverage but won’t be getting the best speed.