I love the ease in which you can create components easily, it allows me to get my job done quickly without having to spend hours researching an API for something new or different from what we are already using! It has been great working with them as they continue to develop their product line and make major changes to improve usability even more than what we currently implement! Great team overall! No real complaints here at all! We use tapestry in both internal and external applications used by multiple agencies within the US government.
They help us build web apps so we don't need to worry about building those specific features ourselves.