You may remember back in March when Samsung announced the Galaxy S6 and Galaxy S6 Edge at Mobile World Congress, that they also announced Samsung Pay. Which hasn't really been launched just yet. And the main reason for this is that Samsung wants to be sure it works flawlessly before it launches. The last thing they'd want is for doing mobile payments through Samsung Pay to take longer then just pulling out your credit card and swiping it. Then most people won't even bother with mobile payments and stick to the old fashioned way of swiping their card.
Samsung recently started doing trials of Samsung Pay in South Korea recently, and it should be launching worldwide soon. Insiders are stating that it'll be launching with the Galaxy Note 5 when that is announced on August 13th in New York City. Samsung is using LoopPay's technology to do mobile payments instead of just NFC like Google Wallet had been doing. This is Samsung's competitor to Apple Pay, which means they need to have their A-Game. Samsung stated that they are currently working with banks and credit cards in Europe, like MasterCard. They will be using MasterCard's Digital Enablement System (MDES) which is actually the same method that Apple is using for Apple Pay.
Because Samsung is using LoopPay for their mobile payments system, they are actually doing it a bit different than Apple. Samsung Pay supports Magnetic Strip Technology or MST. The reason why this is a big deal is that it means retailers do not need to upgrade their terminals for users to use Samsung Pay. Which is obviously a big deal and one of the big reasons that mobile payments via NFC have not taken off just yet. Using MST allows for Samsung Pay to reach about 30 million merchants at launch. However, Samsung still needs to do some work into getting those agreements and partnerships into place. Which they already have one with MasterCard in Europe, so that's a step in the right direction at least.
Don't expect Samsung Pay to be perfect at launch. As we know, some of these merchants can be and will be stubborn to get these partnerships in place with Samsung for their mobile payments. But hopefully they'll have enough partnerships that users will want to use Samsung Pay all the time.