Super Mario Party Jamboree leaked before October 17, so I emulated the game.
The 4 boards in my screenshot are available at the start, with 7 boards in total. Mega Wiggler's Tree Party is the simple board, Roll 'em Raceway's medium, and Rainbow Galleria and Goomba Lagoon are complex. You unlock extra boards during the game.
Jamboree's new gimmick is teaming up on each board with a Jamboree Buddy. Each Buddy does something special. With Donkey Kong you can barrel blast to other spaces, and with Mario you can roll two dice. Buddies let you repeat actions, which helps when buying an item from a shop, or a star from Toad, but doesn't if you pay twice the coins at a toll, or land on a Bowser Space to repeat his event twice. Nintendo did these teams before in Mario Kart: Double Dash, now Mario Party.
Players can go 10, 15, 20, 25, or 30 turns, and turn minigame help and motion minigames on or off. Minigame selection can be random or by vote. You can set star handicaps for each player, so worse players can still win, and movement speed can be fast or slow. Each CPU player has an Easy, Normal, Hard, and Master difficulty setting.
In boards, the left stick opens a menu of reactions, like "yes," "whaaat," "thanks," "sorry," "congrats," "nice," and "betrayal." This menu is locally accessible, but really opens communication between players in Worldwide mode, while limiting the griefing and preventing the grooming that would happen in an unrestricted chatroom.
Players looking to test their skills can switch Party Rules to Pro Rules. Under these, players go 12 turns, and at the start, a bonus star is announced, and an item is chosen. No Chance Time spaces stay on the board, and item minigames don't occur. Items in shops are limited in number, stock is shared between shops of the same type, and star stop spaces and their locations are fixed for each board so they are easier to predict. Boo steals a fixed amount of coins, hidden blocks don't appear, the homestretch doesn't have a special event, and players vote for minigames.
Jamboree has over 110 minigames, more than any Mario Party. Nintendo adds new minigames, like Luigi Rescue Operation and Yoshi's Mountain Race, and refreshes old minigames, like Platform Peril and Snow Brawl. Minigames are mostly delightful and skillful, and not just filler. The game's meant for multiplayer and it's best with people you know, like your friends, or your family. I play with my family, and if short a player or 2, we will gang up on a CPU or 2. If nobody will play, Worldwide mode lets you play online.
If you like Mario Party you will like Jamboree. If not, skip Jamboree. It's a highly replayable Mario Party with high developer effort.