Devin T. Hagerty wrote in his book - South Asia in world politics
“The invading Indian forces outfought their Pakistani counterparts and halted their attack on the outskirts of Lahore, Pakistan’s second-largest city. By the time United Nations intervened on September 22, Pakistan had suffered a clear defeat.”

In his book National identity and geopolitical visions, Gertjan Dijkink writes –
“The superior Indian forces, however, won a decisive victory and the army could have even marched on into Pakistani territory had external pressure not forced both combatants to cease their war efforts.”

Dennis Kux in his book India and the United States estranged democracies writes -
“Although both sides lost heavily in men and material, and neither gained a decisive military advantage, India had the better of the war. New Delhi achieved its basic goal of thwarting Pakistan’s attempt to seize Kashmir by force. Pakistan gained nothing from a conflict which it had instigated.”

“The defeat in the 1965 war led to the army’s invincibility being challenged by an increasingly vocal opposition. This became a surge after his protege, Zulfikar Ali Bhutto, deserted him and established the Pakistan People’s Party.” – says BBC Report http://news.bbc.co.uk/2/hi/south_asia/3227709.stm

A region in turmoil: South Asian conflicts since 1947 by Robert Johnson mentions –
“India’s strategic aims were modest – it aimed to deny Pakistani Army victory, although it ended up in possession of 720 square miles (1,900 km2) of Pakistani territory for the loss of just 220 square miles (570 km2) of its own.”

An excerpt from William M. Carpenter and David G. Wiencek’s Asian security handbook: terrorism and the new security environment–
“A brief but furious 1965 war with India began with a covert Pakistani thrust across the Kashmiri cease-fire line and ended up with the city of Lahore threatened with encirclement by Indian Army. Another UN-sponsored cease-fire left borders unchanged, but Pakistan’s vulnerability had again been exposed.”