I used sprucetips collected this spring & froze, in a recipe from Gordon Strong's "Brewing Better Beer" for "Ben Franklin's Ale." IMHO it turned out pretty good. The recipe called for 1 quart by volume - I really prefer weights for consistency. I was a little short, maybe 8/10 of a quart. Spruce tips were added at 60 minutes in a 90 minute boil. That should have extracted all sugars and flavor.
I can't say I really taste or smell the spuce, but there is a definite after taste and tongue coating that I attribute to the spruce.