I do like finger grooves.
+ I'm an architect. I was paid to obsess over dumb little visual details for decades, and hey I just like the way they look.
+ It's a nod to history. Finger grooves are a traditional German detail, and Germans respect that.
+ I have small hands and scrawny fingers, and like the secure feeling of my grip "sinking in" to the wood a bit.
+ The center the of the grooves's length is invariably near the rifle's balance point. This makes a heavy rifle easier to carry, is a good reference for a consistent grip between shots, and gives me just the right muzzle-heavy "hang" when sliding my fingers to the rear of the grooves. (With irons that is...all bets are off with a big scope.)
BUT...it's just a detail. Don't pass on the HW 35 just because finger grooves are absent! It's a classic rifle with many other virtues. The current stocks give it a more contemporary look, and HW is putting some nice walnut on the E these days. I love the oldies (1967 HW 35E w/22" barrel in this shot), but to each his own.