Yes, but as I noted in the comment, the deeper they go the more the record gets smeared. The last few meters of the GISP core (Greenland) weren't really useful. I think it's because the ice is moving, and near the bedrock it's somewhat anchored, so the ice layers get "stretched".
Still, it's quite an accomplishment, and this is a great dataset for comparison. It might help figure out why some Antarctic areas are cooling and some areas are warming. (Then again, it might not.)
Being in Alaska,I have the opportunity to observe ice and snow on a seasonal basis. One thing I have noticed is that sediments get moved out after a while; they migrate out of the ice leaving pure ice behind as the snow recrystallizes over and over. Of course their core sample is fairly long, almost 2 miles, so it probably does show layering with fair definition. But at depth there would be time for the ice to purify itself. If they can count half a million layers, that in itself is remarkable.
Actually, I beleive the Greenland iceplate is much more dynamic in its movement then the antarctic one. It could be that the samples from this ice field are not as effected by "smear".