I needed a couple of additional functionalities not offerred by the button directly and I emailed the developer. He clearly understood my problem and he suggested a workaround to build my functionality using this plugin. And like others have said, he was amazingly fast in responding (despite the holiday time). Great customer service and willingness to help.
If at all I have to point out any opportunity, they can make it a little easier to set the parameters. The parameters are separated simply by a pipe symbol "|" and when you have to set a lot of parameters (like in my case I had 3 text boxes and 1 drop down), it becomes easy to loose track of the "|"s. But that's a minor one.
I give it a 5/5.