Me thinks me will try Hard after this campaign map is done (currently been doing Default runs pre and post-patch), but I will agree with Alastar and Stabbey that the AI (on Default) needs work. Nowadays I see it just... not doing much with its units, even if they have something like 15+ hunters/grenadiers/troopers with zeppelins and fighters, other than sitting in base. They will send three or five "scout" units to establish bases, but this happens way too slowly, in one direction and they tend to get clobbered by Hunter rushes.
On the campaign map itself, the AI is all aggressive and good - it caught me by surprise in the early game by taking away one of my "core" territories through amphibious assault *and* immediately building a factory on it afterwards to rushbuy units (attacked my capital to delay any response I could muster in the meantime). I thought that was a particularly pleasant touch, but come the mid and lategame, unless you are like attacking their capitals, the AI rarely sends more than 8-10 units. It will repeatedly send in 1 or 3 unit on suicide missions to my lands guarded by 10+ units. AI's threat calculation here needs a bit of work in this regard. They also definitely need to be building more naval warships (Dreadnoughts and Ironclads) for mounting naval invasions - they will use Cards to get those ships in play, but I have never seen the AI actually build them on the Risk Map, let alone Skirmish.
