The integration is so good we can't understand why it's not more popular! We've been using this product since its first release several years ago now, and I still don't know what all they could possibly add - there was just no need when you already had everything taken care off by another application (the one from which you're integrating).
So far i haven't met any problem or issue while working with them. Easy installation process & great support service. We used integrate our accounting/ERP systems together to create seamless workflows between both applications without having to rely on 3rd parties like middleware providers who will only charge extra fees but won't provide quality services.