It's hard to properly weigh in on such a perversely cute board game. The minigames are preschool-level at best, often requiring nothing more than simple gestures to complete. Dialogue is so basic that a five-year-old kid could whip up something more profound. Even the Community Chest-style spaces you land on put the little guys into are right out of a fable or moral tale (helping kids across the street, visiting old folks). But somehow its invasive, saccharine cuteness manages to generate enough interest that hardened Mario Party vets will want to play a round or two.
After those two introductory rounds, however, everyone's going to jump ship. The minigames are few and far between, spread out by massively long stretches of sitting still, watching the computer or other players take their turns. How fun is it to watch other people roll dice, sift around a shop for bizarre items, play inane minigames and slowly decide which path to take on the board? Um, it's not. Ever. It's not fun in Mario Party and it's not fun here. On that level, these two games are pretty much the same, save for one wholly damning nugget of curiousness - none of the minigames in Party On! are multiplayer. There's little to no interaction with any player at any time, making this a repetitive, annoying board game played in total isolation. If everything else were fun we'd deal, but it's just not.
There are also "Gotchi Games" that play like keychain games you find in a supermarket or toy store, complete with chirpy music and irritating sound effects. These are also to be avoided. After waiting for your turn to come back, you may land on a space that makes your 'gotchi sick, forfeiting your chance to make any progress. After another long wait, you'll find the sickness still churning along and you miss another go. Hooray! Nothing like spending four to five minutes at a time doing absolutely nothing.
The point to all the madness is gaining enough popularity points on the board so the insane 'gotchi residents will elect you president. Raising awareness costs money, and if you happen not to win any money by landing on sporadically placed squares, you can't buy any campaign merchandise. Then the game turns into "sorry random chance isn't in your favor. Go screw yourself and stop playing, you suck." Throw in the fact that all the menus are navigated with the d-pad and not the remote and things start to look horribly thrown together and neglected.
Everything takes too long to get to, and once you're there, it's just not any fun at all. Party On! is admittedly adorable, and honestly a lot more fun to look at than Mario Party 8, but serious attention needs to be paid to the content, frequency and relevance of the minigames. If you're looking for a mindless game for kids to play, you could certainly do worse (the charming visual style is enough to keep kiddies entranced), just be aware of how watered down everything is. If you're trying to decide between this or Mario Party 8, may we suggest WarioWare: Smooth Moves?