I've heard both pros and cons on the subject. Some get upset and view this as lazy writing. Your character gets out of trouble via supernatural assistance. Others shrug and accept the presence of heavenly beings in literature. After all, they're in the Bible.
I belong in the second camp with one important qualifier. As long as the angels are written in accordance with scripture, I don't have a problem. If people are worshipping them, praying to them, or are elevating them above God, it goes in the trash. Period.
That said, the scripture tells us to be hospitable to strangers because some have entertained angels unawares. Angels are called the servants of the heirs of salvation. They're heavenly messengers, such as the angel, Gabriel, who came to Mary and told her she'd been chosen to bear Jesus Christ. He also brought an answer to prayer to Daniel. A host of angels came to Elisha's defense in the Old Testament.
Most books with angelic intervention are labeled speculative fiction. What's your take on the subject? Have you read any books where the hero or heroine is rescued from a jam by an angel? Do you ever write angels into your manuscripts?