It is common in informal speech and writing but is neither rare nor wrong in serious discourse. There are 20 meanings listed in oed's entry for the word pretty, four of which are labelled obsolete Pleasing or attractive to the eye, as by delicacy or gracefulness.
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See examples of pretty used in a sentence.
We can use pretty as an adverb, before an adjective or another adverb, meaning ‘quite, but not extremely’
… that's a pretty hat you're wearing The sofa was covered in very pretty flowery material She's got such a pretty daughter She looked pretty in a simple cotton dress.
Pretty (comparative prettier, superlative prettiest) pleasant to the sight or other senses Attractive, especially of women or children [from 15th c.] coordinate term, near synonym quotations coordinate term If you describe someone as pretty, you mean that they are attractive
She's a very charming and very pretty girl.
