Aptana is a very good tool to write your Python scripts in. And since ArcGIS is equiped with loads of opportunities to use Python, Aptana is a good choice for developing your Arcpy (= ArcGIS’ site package for Python) scripts. Enabling Arcpy within Aptana is not very complicated, but you need to set a few configurations right. And if you forget this, it can be quite time consuming to find the solution.
So: a few pointers.