I don't know what people see in the Mario Party games past 4, all those played cheaper and lamer with weird board gimmicks.
But I'm still keeping an eye out for the reviews.
5 introduced Capsules, which were a poorly implemented new item system but both 6 and 7 took it and vastly improved it into something even better than the standard item system from 2-4. In 6 and 7 you could place Orbs on the board as traps and essentially take up real estate. It added an extra layer of strategy and further rewarded players for winning minigames (since you'd want to use coins to buy Orbs frequently since they were so vital). 6 and 7 also brought in boards with unique rule sets which gave more variety and made each board require different strategies. MP is at it's best when there's a healthy mix of luck and strategy, something 6 and 7 excelled at. The best games in the series are 3, 6 & 7, imo.