Recently read a book titled When Kings Rode to Delhi by  Gabrielle Festing, which is available here. In the book there is a chapter on Sivaji called The Mountain Rat, title supposedly given by Aurangazeb to Sivaji. After the killing of Afzal Khan, this is what the author has to say:

 In the eyes of a Maratha, who believed himself Bhavani’s chosen warrior, such treachery was meritorious, and the slaughter of the envoy was an act of devotion.

Further the author describes various exploits and acts of Shivaji and in the end he says:

An attempt has been made to cast a glamour about him and his hordes, as patriots, deliverers of their country from foreign rule, devoted heroes who faced desperate odds. After a dispassionate survey no glamour remains. Sivaji was a typical Maratha of the best kind that is to say, he was as unlike the Rajputs from whom he claimed descent as the South African Boer from the good Lord James of Douglas. Never, unless they were driven to it, did the Marathas fight a pitched battle in open field ; the joy of fighting, which made the Rajput deck himself with the bridal coronet, the desperate valour which heaped the plain of Samugarh with yellow robes till it looked like a meadow of saffron, was incomprehensible to the wolves of the Deccan. They fought, not for a point of honour, or because they enjoyed fighting, but in a commercial. spirit, for the sake of what they could get; their word for “to conquer in battle” means simply “to spoil an enemy.” The Rajput was indolent, when not roused by pride or the thirst for battle; the Maratha was untiringly energetic as long as he had anything to gain, but would sacrifice nothing for pride or scruple.
This must be said for Sivaji, that while he lived his followers were forbidden to plunder mosques or women ; after his death his son pursued a different policy.