I have been using mobikwik for quite some time now. and my experience is as follows.
Sites like grofers give good cashbacks and till now lots of issues like secure connection creation screen stuck etc have happened earlier.
fake cashback on justeat site as after calling them no helpful replies.
electric bill payments are a nightmare as the amount will get updated after 10 days sometimes. I have complained about this and no good outcome has come.
bookmyshow cashbacks are having lot of issues.
mobile recharges are fast but coupons many times don’t work at all.
wallet to wallet transfers are fast.
email id are mapped to gmail id(first 5 only) stored on your accounts list. other mail id usage is difficult and not possible.
transfer to bank account is useless as it is charging 4% commission every time.
all in all only good till offers are there otherwise payu is better.