FiatBuys less and less things over time (prices of things to buy go up)
Very high fees to send money across country lines
Costs atleast $20+ for a single (same-day settled) wire transfer
Can buy things quickly & conveniently
Can pay taxes
Can be mostly anonymous to do illegal activities
Is completely Regulated and controlled by governments
BitcoinBuys more goods/services over time (prices become cheaper as time goes on)
Minimal fees to send money to another country
Minimal fees for same-day settlement
Not convenient to use directly to buy things (however can be used indirectly for scaling options)
Cannot use to pay taxes directly to government
Is completely tracked and not very anonymous for illegal activities ; blockchain has immutable record
Cannot be regulated or controlled by governments
More suggested reading re: Bitcion:
"Hacks & puppets & forks - how to destroy bitcoin":
https://bitcointalksearch.org/topic/hacks-puppets-forks-how-to-destroy-bitcoin-1834310 Fiat's usage isn't really decreasing, while the prices of items goes up the pay for work also goes up, which is how inflation usually works (although it is still annoying for anyone who wants to save money and is not needed in society).
I would also argue that while Bitcoin is not very anonymous for illegal activities, it's better for them than online fiat (e.g. banks) because while the transactions are held on the blockchain they are based on pseudonymns which can be changed all the time.