Well, simply put, it's a proprietary development software used to develop the Microsoft Business Solutions product line, (Dynamics & Small Business Financials). For the time being, anyway.
Dexterity gives developers the ability to write seamless applications into the Dynamics product line without actually modifying the original code. A truly great concept.
We prefer to use Dexterity and C# v.s. tools such as Continuum and VBA because of the added speed of development by utilizing the Microsoft Dynamics code into our own applications. Not to mention we have 30 years+ of dexterity and C# libraries built up.
Of course, we are developing much of our code in C# AddIns lately. This allows you to purchase the libraries and have your own C# developers continue the product maintenance if you choose that route.
What we can do for you, (Certain funtionalities and capabilties may be limited between the Microsoft Dynamics GP).