I installed this plugin for use with our training and development website, and I've been able to integrate it without much of a hassle. We even did test transactions, including refunds, and there were no problems. A good product that I'm sure will continue to get better over time. I'd like to have the ability to change more of how some of the screens looks (like the layout, not just the fonts and colors) so hopefully we'll see a few different themes in the future.
I'd recommend it and use it again. I'm not worried about the transaction fees... who doesn't charge transaction fees? Banks charge more directly, and this works flawlessly, so in my opinion it's paid for itself, because I don't have to deal with the hassle of contacting the bank whenever something doesn't work right.