Dawn of Discovery is best thought of as Civilization Lite ... or better yet, Colonization Lite ... or better still, Anno 1701 Lite, just set in 1404 instead. It's actually a game in the Anno series, made by the same team, and in Europe it's called Anno: Create a New World.
The setup is that King George is old and ailing, and his kingdom is Rabble Rabbling because they don't have enough food. He has two sons, one (the eeevil one) wants to turn the Rabblery into an army and march on lands in the north, the other (the good one) wants to sail south to the kingdom's otherwise unused islands and develop new farmland and colonies there. We're stuck in the role of Goody Two Shoes and don't get a choice in the matter, so a-farming we will go!
As with predecessor Anno 1701, the Pocahontas-esque art style reflects the Disneyfied politics and historical view
of the game. There are a bunch of islands south of England IRL, but they qualify mostly more as "big rocks" than islands, certainly not these big tracts of arable farmland that can be colonized. The only "islands" that fit that description (though more west than south) in the area are Ireland, Scotland and Wales ... all of which were violently occupied by England before 1404. We just gloss over all that, though, for the sake of someone's game design idea, so the story portion of the game can be divided into self-contained "chapters" centered around clusters of individual islands.
And as with predecessor Anno 1701, though I think it has very iffy politics, that isn't really a factor in why I don't care for the game. The main reason is simply that a PC-style civ-building game is a bad fit for the DS's relatively tiny touch-screen. Doing certain things like building new roads requires the screen to be centered on the spot you want to begin building, which is inexplicably imprecise and finicky. Sailing between islands is a chore as you have to drag the navigation cursor to the edge of the screen, stop and scroll the screen, repeat, repeat, etc. This gets even more fun when you start getting chased by pirates later in the game. The menu system consists of tons of scrunchy icons that it's not always clear what they are. Eventually you're forced to conquer lots of other islands, and doing this is tedious thanks to a very low limit on ships that you can have, and establishing a foothold in enemy territory requires you to sacrifice one of those ships for some inane reason. Combat is also as simplistic as it gets with only one unit type, generic Troops, available for production, and battles basically degenerate into who can pump more of them at the other the fastest.
Civ-building games are not strongly represented on the DS, however, so I guess this becomes one of the better options by default. The Anno games basically do what a lot of PC games have done before them, just more simplistically and with a cutseified and (somewhat) more noob-friendly interface. I guess they're fine if you're really jonesing for civ-building action specifically on the DS for some reason ... if other platforms are open to you, however, there's heaps of better options in this genre than this.