The ease in which you can build up your model from scratch or modify existing models using either Python scripts/API etc., as well having great graphical user interface (GUI).
I have been able use this product without any prior understanding about it but once familiarized i found that my job became easier than other products like QGIS where there are some very complex operations involved just by clicking few buttons! It's not free so be prepared if needed large volume datasets need processing!! We used Arc 10 GDB files into one file format compatible between different tools we were working upon at our end & also had geospatial features added before exporting them out again after adding more attributes later down stream.- Data cleaning- Merging multiple attribute tables together.- Creating new layers within an already created dataset.- Exporting specific layer(s) only when all else fails while.