There is more to it than them getting their money instantly when you get paid.
They also will pull a stunt where you just listed 5 items all on 3 day auctions which they charge $1 each to do vs 5-7-10 day auctions.
If you have just had auctions end that you will not be paid from epay for 2-5 business days they will cash out (release payment to you) one of your auctions immediately so they can scam the 3 day fees ahead of time instead of waiting until your auctions end.
Then they will drag their feet releasing the other ended auction payments that have been made by customers.
Meanwhile you are shelling out the shipping for items you sold and were already paid for but epay is "processing" your payment transfer.
Bottom line, they hold your money and make bank on it while you wait.
That being said, they still are the best way to sell your items to a worldwide audience and you can list items for free so it is like having a free window to the world of you wares.
All it takes is one good auction where 2 huys get into a pizzing match and Boom you make more than you ever would selling at a flea market, brick and mortar, etc.