It really is 'very close' to the Trevi fountain, probably under 30 seconds walk away round the corner. Get up early and enjoy the fountain without too many people with you morning coffee.
Great location for exploring the rest of Rome as well, most of the major sites in 10-15 mins walking distance.
It's not a hugely touristy street but if you like going to bed early you might find your sleep a little disturbed by others out and about on the town until the early hours.