lyrical
wax lyrical about (or over) talk in an effusive or enthusiastic way about something.
☞ Wax (from Old English weaxan) was used to mean 'increase in size' right through until early modern English, but since then it has been superseded in all general contexts by grow. It now survives only in certain expressions, especially with reference to the moon's monthly increase and decrease (waxing and waning).
2013The Register Brian waxes lyrical about Amazon, prompting Greg to ask: why are CIOs everywhere falling in love with private clouds?