L'Eau du Trente-Quatre is the latest from French niche line Diptyque, and is meant as the second chapter to (or the springtime variation on) the story started with 2011's 34 Boulevard Saint Germain. If you remember, that one was meant to capture the essence of Diptyque's flagship store in Paris, hence the street address; both "chapters" were developed by perfumer Olivier Pescheux.
I liked 34 Boulevard Saint Germain, but like Kevin, not so much that I was tempted to add it to my buy list. L'Eau du Trente-Quatre won't make the list either, but I do like it a little better. It's brighter, crisper, greener, and more summer-y, and while you will still find echoes of 34 Boulevard Saint Germain's "Diptyque — The Greatest Hits" theme (the most obvious nods to my nose are to L’Ombre dans L’Eau and L'Eau, but there are also elements of Oyédo and Do Son, among others), it's possible to just enjoy it as a lively variation on a unisex summer citrus cologne, with a nice kick of spice, decent longevity, and a musky woods dry down with a light powder finish.
It's enjoyable and easy to wear, but for my money, not as much fun as some of Diptyque's other summer citrus possibilities, like L’Eau de L’Eau (another Olivier Pescheux, spicier and darker than L'Eau du Trente-Quatre) or the still-crazy-after-all-these-years Oyédo (fizzier and sweeter).
Diptyque L'Eau du Trente-Quatre is available in 50 ($100) and 100 ($135) ml Eau de Toilette. The notes include bitter orange, verbena, lemon, grapefruit, lavender, nutmeg, juniper berries, cinnamon leaves, birch tree leaf, geranium, tuberose, Virginian cedarwood, patchouli, incense, labdanum and musk. For buying information, see the listing for Diptyque under Perfume Houses.