The answer is that it often is not, at least for most people, most of the time. Eventually it will be the best payment system, but it needs to develop further, gain more adoption, and get over the scaling obstacles. Even so, Bitcoin is already the best payment system for certain use-cases, such as sending money across borders, or receiving money from someone you don't trust (which helps further in cross-border transactions).
Yes it is the best part system since a lot of people and markets accepting it as a means of payment. I am hoping that in spite of this they can still secured bitcoin and as much as possible bitcoin shouldn't involve in different crimes so that there would be no reason to banned it.
Yes, bitcoin is a better payment transactions, It will minimize the time, effort and transaction fees than doing transaction in the bank.