If you've read even one page of Sentimental Education, it will come as no surprise that Flaubert loves him some detail. This guy is a describer, that's for sure. And he'll describe literally anything: clothes, people, furniture, feelings—you name it.
In a letter to his fellow writer George Sand, Flaubert claimed that he was "trying to write harmonious sentences, avoiding assonances" (Source, p. 89). Translation? He spent a lot of time choosing the right word—some people would even say too long. The point is, he didn't hammer this thing out a la Jack Kerouac-style on one long scroll of paper. No, Flaubert plodded. But the result can be pretty cool.
In fact, Flaubert is a pretty big deal in France. Since his day, critics and readers alike have been obsessed by discussions of how beautiful his prose is. Now remember, we're reading the book in translation (from French), but there's no question his writing can be entrancing. Check out Frederick's first reflections of Madame Arnoux:
Meanwhile his attention was directed to a long shawl with violet stripes thrown behind her back over the copper support of the bench. She must have, many a time, wrapped it around her waist, as the vessel sped through the midst of the waves; drawn it over her feet, gone to sleep in it! (1.1.26)
All that for a shawl? Yowza. (Check out our section on "Symbols" for more about clothes.)
One last style-related thing: there's been a lot of talk about how much research Flaubert did to make sure that Sentimental Education would be politically and socially accurate. That's great and all, but the guy can definitely take it a tad too far (in our not-so-humble opinion).
For example, remember the tour Madame Arnoux gives Frederick at the ceramics factory outside Paris? She starts using all sorts of technical terms and elaborate descriptions to the point of total tedium. Maybe she's just nervous, but still—it just doesn't end. Even Frederick has had enough: "Frederick was starting to get bored." Really? Us, too.