I just finished this lovely pocket-sized collection after nibbling at it on the train, in the elevator and, yep, on my lunch break, and I did find it a pretty ideal way of consuming the poems therein. I know the title refers to when Frank O'Hara supposedly wrote the poems but it doesn't have to, they're a bit of richness in the middle of everything.
O'Hara had a whirlybird head on his shoulders and so you get everything as it comes through his head, especially people and places and art (movies most of all). It's an urban type of poetry, caught up in everything at once (the city is of the New York School bohemia vintage). His tone is mostly conversational, chatty even — he'll mix memories in with references to art, and then make a scatological pun. I've heard him described as an especially social poet, which seems right. He's pretty Whitman-esque, being caught up with the currents of the place and time, having an enormous appetite for culture, and being genuinely desperate for human connection (and unembarrassed about bodily functions).
Here is "Ave Maria," which is my favorite.