In general, I couldn't handle it – it's not my type of map. Too many monsters, and they're all very strong, plus a huge map and a lack of active enemies and your own castle. I thought I'd try it on Recruit difficulty, but the auto-battle doesn't work. Even playing each battle manually, there are hordes of Daughters and Griffins even on Recruit. In general, it's for those who like to grind against tough monsters.
Considering the hero's level-up speed and level reset (and, consequently, stat reset) in later missions, the map size doesn't seem justified, in my opinion. There's no point in running around and exploring the map. It would make sense to show the final point of the map and an approximate shortest path. By the time you reach it, your level will be around 30. Long wanderings are not good for campaigns, in my opinion. 2-8 weeks to complete such a map, visiting all the upgrade locations, is just right.
I, on the other hand, like maps where you have to carefully plan and think through each battle, and when there are many quests – that's very good.
And no one is saying that you have to attack everyone at once. There are adequate opponents for your army, and within one or two days (depending on whether you have logistics or boots), there's an unguarded fort, and next to it, there are buildings for creatures of the first and second levels (you'll have to work for the beasts, but getting a scout building is not difficult).
But campaigns that are too fast are somehow boring; you just start, and it's already over. You don't have time to explore everything, to level up your hero. But I like long missions! :D