The example shown is quite large and very oblate. There were many such; I picked this one to show the slight blush, which was less typical. (Or perhaps it's a sunburn.)
My other unblushed sample (photo below) is smaller and more classically shaped, also representative. Both are a little ribbed and have a faint grassy aroma. Both are rock hard in early October.
Inside, fine-grained white flesh tinted green is crisp and moderately dense, with both crunch and chew. Zabergau's flavors are tentative and delicate, balanced and with the merest hints of kiwi and lime. There is a little astringent feel during the chew, too.
I'd call this apple tart were the flavors stronger.
If you want a full-flavored apple, Zabergau is not for you. But its texture is good and its unusual subtlety is interesting in its own right.
National Fruit Collection says Zabergau was raised from seed (that's the "Reinette" part, by the way, nothing to do with princesses) in Germany from 1885.
An oddity: Some of the flesh torn with my teeth browned almost immediately while other more "cleaved" surfaces remained clear.
Note that some other reviewers find more to this apple than I.
Orange Pippin says this apple "tastes of nettles when straight from the tree," which raises the question: You eat nettles?