Denmark's not BAD, per se, but yes, it can be a bit uninteresting. They're excellent at what they're designed to do: raid and pillage, and yes, sending a load of Berserkers out to just completely get rid of everyone's tile improvements can be effective, but it's not exactly all that interesting. One thing I do think people ignore is how well the Ski Infantry pairs up with this. Any Berserkers you still have from earlier in the game can upgrade into them and keep the Amphibious promotion, and with that exploit of embarkment movement staying on the unit when it returns to land, Ski Infantry are FAST, and can potentially move along a lot of terrain like it was Railroaded, while pillaging loads of tiles in one turn. But eh, I honestly think a proper Norway civ with that as its unique and the Stave Church for a UB would be best, I do believe each civ should just have only one UU, and Denmark should get a building or improvement in its place. They don't need a Longboat, the UA already represents Longboats as a fast, efficient medieval troop transport: they could manever quickly across seas and could land easily on beaches. That's all represented by the no-cost, faster embarkment. As I said, they're not the best civ, but their abilities definitely well represent the medieval blitzkrieg tactics the Vikings were so fond of. Either they should get a modern UB to represent their status as a solid, progressive nation in the world today (I do like the idea of a Hospital/Medical Lab replacement), or just go full Viking and have like a Runestone UI that gives Culture/Faith and additional production to Melee units. I like that second idea a bit more, unique improvements are always nice for flavoring a civ well.