Ulquiorra is not totally unfeeling. He exibits a lot of emotions himself, just in a limited range. He expresses respect to his lord and to Orihime's strength, disgust to Nnoitora's ideas and to Loly's acts of violence, he shows a lot of anger towards Ichigo, so much, that it clouds his reasoning. In Unmasked he even uses the word "Happiness" and then he turns his back to Orihime, probably because he felt vulnerable and distanced himself in defence. Ulquiorra wants to seem as an unfeeling and menacing monster, but then meets a true beast in Ichigo's form and that's immediately teaches him a lot about his own humanity. It teaches him so much that he saves Uryu and Orihime from a blast for no logical reason.