Because Arno was designed relatively recently, in 2007, while I'm sure I've seen this beautiful typeface, even accompanied by its name, I hadn't been particularly aware of it, until my curiosity was piqued by its mention in a thread here.
It is described as drawing its inspiration both from Venetian typefaces (which I understand, perhaps not quite correctly, to mean those of Nicholas Jenson) and Aldines.
That's certainly a good choice; many fine typefaces were inspired by Jenson, such as the Doves type and Centaur, and the roman of Aldus Manutilus, although it gave rise to fewer direct imitations, was highly influential on the romans that came later.
Since many type designers tried their hand at least on one Jenson, this style apparently being regarded in some sense as the pinnacle of the art, perhaps the only thing that should have surprised me about Robert Slimbach's choice to soften and modernize the Jenson by admitting an influence from the Aldine is why it took so long for someone to try this.
But my initial reaction was different. My initial reaction was that this was a bold and adventurous choice; if one's goal were to create a dignified, prestigious oldstyle... that would still be a huge popular success... then, shouldn't one aim more closely to the mainstream?
So I wondered why he hadn't chosen the Aldines and the Garaldes, like Garamond, as his starting point instead.
And that started another chain of thought.
My own taste runs to "invisible" type in the "crystal goblet" sense - in that, if I felt myself to be able to engage in type design, this is the kind of type I might try to design, feeling the world has a need for it. While I would probably admit many influences - such as Caslon, corrected for a heavier ink impression, and early Scotch Romans - if one wishes to describe the area of design space I'm thinking of as simply a blend of two typefaces, I'd say Baskerville and Century Expanded.
Perhaps 300 years from now, when the popularity of Times Roman has run its course, some type designer will become immortal by exploring the design space between Caslon and Times Roman.