Using this from 2014, first was using on their website platform and now their Android app.
Never faced any major problem, will share my personal experience ahead.
Pros: #1 Available on PC and SmartPhones #2 Recharge available for all network and circles #3 Virtual Cards available #4 Now you can pay several merchants with your Freecharge account #5 Can shop on Snapdeal with freecharge wallet
Cons: #1 All tariff plans of all network are not available #2 Tariff plans are not frequently udated #3 Sometimes payment and recharge fails continuously
Verdict: If you are looking for online recharge platform then I think this is the good one to try, they continuously add some of new feature so its good to try.