I used this app to pay in bitcoins and am completely satisfied with this product.
Regardless of whether you use it on your phone or from your web browser, the user interface stays the same. You have to enter the wallet address of your recipient and choose the amount you want to send, either in coins or in fiat currencies.
The best part is that when you send coins, you can allocate any sum in fiat currencies. So, I just entered the amount of dollars I want to send, and it gave me the corresponding amount in the chosen fiat currency. All transactions I made were processed instantly, and I have never experienced any issues on the receipt side.
Another big plus is their fee structure. First of all, it is very competitive (for example, sending 10BTC would incur 0.01030779 BTC transaction fee). Second, they have different fees according to the required urgency: minimum transaction fee, within one hour and fastest.