I just wanted to give some more impressions, since there is no OT and people were asking for some. My wife and I played the two rounds of the board game needed to unlock everything else, the balloon game, and the island game. To preface, I am a fan of the main animal crossing games, and my wife has just gotten (really) into happy home designer but hasn't played any of the main games.
The board game was a fun, solid, but basic board game. There are actually way more events than just what the calendar shows, and there is some sort of special space to land on more often than not. Usually these will let you play a game or buy a card that have effects on the board, erase debt, or dice cards let you move a specific distance. The holiday events vary quite a bit in what they do, but usually change all the spaces to something different that causes various holiday events to occur (like fishing spaces for different rarities of fish) and are a good time to have the dice cards. The real meat of the competition starts when the stalk market opens in the second week. It basically lets you gamble your money on turnips from Joan. In our first game I took a long shot gamble on them that really paid off and got me something ridiculous like 80,000 bells, but I got really lucky. Overall, I thought the mode was fun, but just ok. My wife on the other hand really liked it, and wanted to play again right away. I'm really curious to open up more of the customization for the board.
The balloon game was simple fun. Spyroflame had a pretty good description of it so I don't have much to add. After popping the balloons you need to land on a moving island that has multipliers on it, and if you fall in the water you lose everything. This led to some intense moments and laughter in our house. We played if for about 15 minutes, but had a pretty good time doing so.
The island survival game was probably my favorite. We just played one easy level on it, and used a pass the pad style where we each played for one of the characters and swapped off on the third. We only played it once, but it seems like all of the amiibo cards have decent variety in their abilities. For example, I used Kapp'n and was excited to see that he had 6 movement points, which is a lot, and that he can move through shallow water. But this came with a drawback, because he used two movement points when traveling on land. While we were playing, my wife said "This seems like a game you would like to play by yourself." and I think she's right. It has just enough light strategy to be a good killing time type of game by myself, but I think it was more fun to play it as a team and talk strategy.
Overall so far, I'm glad we bought it. We didn't really take to the new mario party well so we were jonesing for a new board game-game to play. The amiibo usage is just a touch sketchy, since the main game at least shows that they don't really need them with the (human) villagers, but since they come with it for the price of a normal game, it isn't so bad. I'm hoping someone makes an OT soon, because I'd like to hear what others are thinking too!