the blackberry's tartness replaces a sour flavor. i prefer tart to sour. i actually dislike the ingredient sours.
Hm. Didn't look like there was enough there to offset a whole half-shot of honey, to me. I may have to play with it...
Also, if you mean the "ingredient" known as Sour Mix, got in a jug, neon yellow, from the supermarket or at an el cheapo bar, that's probably because you don't like drinking HFCS with Citric Acid and Ascorbic Acid and Yellow #5 in it. Try some classics with real fresh actually-squished-out-of-a-fruit citrus in 'em and I'll bet you dig 'em way more. One of my favorite introducers is:
Sidecar:
1.5 oz brandy
1 oz lemon juice, freshly squeezed out of a lemon, of course
.5 to 1 oz of orange liqueur, depending on taste and brand (Gran Gala is good and not as expensive as Grand Marnier; the 40 proof Dekuypers crap is, well, crap)
Chili's will whip you one up if you can tell them what's in it, as will Olive Garden, I've found.

Malpan: Whiskey Sour has no soda and if a bartender at the bar you're at puts soda in a whiskey sour, you should probably just stick to shots and beer there. Also, a SHOT of simple?? That's 1.5 oz of simple, man; that's as much as the whiskey! That's waaaaaaaaaaay too sweet. I mix mine 1.5 oz whiskey to 3/4 oz (half-shot) of lemon and 1/2 oz of simple. Oh, 12bottlebar did a good write-up on this stuff:
http://12bottlebar.com/2010/04/19/the-whiskey-sour-four-ways/(By the by, I mix my simple 2:1 sugar:water, so it's "rich" simple, and I typically use either raw sugar or half brown sugar, half white sugar, if I can't get raw).
PS: Float about .5 oz of red wine on top with the aid of the back of a spoon and you've got a New York Sour and it looks FANCY and tastes even better!
Sometime soon I may have to write up some bitter examples, since I don't seen any Campari, Angostura bitters, herbal liqueurs (except benedictine or chartreuse somewhere up-thread, used only for it's color and strength and totally unbalanced), or anything in here...
Next up: Aamericano, Negroni, and probably something a little sweeter with some bitter elements, too... Hmmm, which one to choose...?