I recently finished this one. I enjoy the mystics, but I'd never read anything by Teresa of Avila before. It's sort of a "how to" guide for a faith journey, beginning in the world with all of its temptations before transforming and eventually culminating in union with God. Though written in the 1500s (and did not benefit from the extensive editing we can do nowadays thanks to computers) the themes are timeless enough to still be applicable to modern times.
If anyone is interested in the mystics, I have found this podcast to be a good listen albeit long. They have nice daily meditations too:
https://cac.org/podcast/turning-to-the-mystics/