It’s the most complete online compendium of early Chinese texts I’ve encountered, and certainly the most robust in its search capability. I would use it for hunting for usage examples of various terms, or for verifying the underlying Chinese for texts for which we may only have translations. For actual citation, as with any internet material, it would be best to corroborate findings in a trusted print redaction.
A nice feature is the little blue radio buttons next to text sections which will bring up a page with the selected text at the top, then below glosses of all the graphs within that particular selection. For example, if I’ve searched for something in the Maneuvering chapter of the Sunzi,http://chinese.dsturgeon.net/text.pl?node=20949&if=en
then choose paragraph Four, and click on the blue button, I get the following:http://chinese.dsturgeon.net/dictionary.pl?if=en&id=20953
Of course, I have a good print redaction of the Sunzi, but this is a very handy way of quickly navigating through a vast collection of material.