In book three of the Iliad by Homer, the Achaians and the Trojans are preparing for battle, and an argument breaks out between the brothers, Hector and Paris. Paris calls out for a brave man to duel him and eventually agrees to fight Menelaus man-to-man (mostly out of shame) to win Helen and everything she has. This, he hopes, will keep both armies from having to fight. Obviously the soldiers on both sides are thrilled, and they relax and prepare for a truce.

King Priam is sent for, and he arrives in a chariot with Antenor, one of his sage advisers. Helen is also sent for and arrives with several of her ladies. 

Helen watches the negations and preparations on the field below from the tower with King Priam, who feels some sympathy for her. As they watch the men preparing for the duel, Priam asks Helen to tell him about some of the Achaian men. Helen knows some of them, including Agamemnon and Odysseus.

Helen describes Odysseus to Priam this way:

“That man is Laertes’ son, crafty Odysseus,                                          
raised in rocky Ithaca. He’s well versed                                     
in all sorts of tricks, deceptive strategies.”

Antenor, one of the Trojan elders (who advocates Helen's return to the Greeks in order to keep more men from losing their lives), adds his own observations about Odysseus. He agrees with Helen that Odysseus is a complex man. 

Antenor recounts a story in which Odysseus and Menelaus came as ambassadors to speak to Antenor, who hosted both men for formal dinner. The two-man delegation was here to negotiate for Helen; though Menelaus was a more imposing figure, it was Odysseus who  "seemed more regal."

When the time came for them to speak to us,
setting out their thoughts quite formally,
Menelaus spoke with fluency—few words,
but very clear—no chatter, no digressions—
although he was the younger of the two.
But when wise Odysseus got up to speak,
he just stood, eyes downcast, staring at the ground.
He didn’t move the sceptre to and fro,                                      
but gripped it tightly, like some ignoramus—
a bumpkin or someone idiotic.
But when that great voice issued from his chest,                                   
with words like winter snowflakes, no man alive
could match Odysseus. We were no longer
disconcerted at witnessing his style.”

So, what Antenor says about Odysseus is all positive. He says the man was gracious and regal in his demeanor, and he was an astoundingly effective speaker. In fact, he claims that there is no better speaker alive than Odysseus. Clearly Antenor admires Menelaus for his physical attributes, but he admires Odysseus, even though he is the enemy, for his abilities as a persuasive speaker.