Awesome. Also they are not down to bedrock, so there is more to the record if they can reach it.
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.)