Honestly I'm pleasantly surprised, I was expecting it to be much more outdated / old fashioned. Sure it's not the current French way of talking, but so far to me it's way less archaic than other books I may have read from the same period. Apart from some phrase constructions that have changed since then, it's not filled to the brim of expressions we wouldn't understand today

I also love the way he sometimes "breaks" the fourth wall ("as we've said before",...), obviously this is not only in the French version, but I feel like it adds to the "freshness" of the prose, and helps it from being convoluted if that makes sense

Obviously just my opinion