You likely know already the story behind 'Summer Crossing's rediscovery and posthumous publication, so I'll skip it, but this novella does show off the talent Capote possessed from a very young age.
I haven't read 'Breakfast at Tiffany's yet, but this is a very different style than the calm of 'In Cold Blood' and the rich gothic of 'Other Voices, Other Rooms'.
'Summer Crossing' begins with Grady O'Neill, a disconnected and privileged Manhattan teenager, on the verge of spending a summer by herself in the city while her parents steam to Europe, and her older sister is preoccupied with her own family in Connecticut. She is newly in a love affair, must contend with family pressure to conform, must deal with the world and her friend seeing her as a woman. The book ends with Grady O'Neill, a disconnected and privileged Manhattan teenager, on the verge of thinking about making a very important decision.* Not that no progression was made, or that character progression is essential....The book flies and has wonderful turns of phrase, but while I enjoyed reading it, I can't tack down exactly why I did. Beautiful babble?
*There's a little more down the road than that, but I don't feel like spoiling the scene by detailing it. Even with that ending I don't feel that Grady made any choice in the matter.