They're a hybrid. I use them in place of Northern Brewer hops occasionally. That's about as close as I can come to describing the flavor profile...a very good & versatile hop in my opinion.
My experience puts them along with those that have a bit of a woodsy flavor like Fuggles (at least my homegrown ones). I made a fresh hop IPA last year with both Glacier and Cascade for aroma, and then dry dry hopped with both, and I didn't think it was the best combo. The citrusy flavors just didn't mesh with the woodsy flavors. I like it for British style beers.
I just bottled a Red Ale-ish beer with Glacier. I used it for the only flavor/aroma hop and it is excellent. The beer is a little sweeter and has a touch of biscuit malt. I also really liked it in a Bitter I did in the spring. Potentially good in a stout, though I haven't tried that.