4 was the stain on the series, and to this day I try to push the memory of it into the shadows of my long-term memory. After coming from Mario Party 3, it was easily the biggest let-down I have seen from almost any series. In the third installment you had lots of really clever games that could test your skills, as well as strategic item usage like the reverse mushrooms. Going to MP4 was like going from t-bone steak to bologna.
Then Mario Party 5 came out. Part of me knew that the team still had it in them to make a totally awesome Mario Party game, so I checked it out. Thank god I did. Mario Party 5 rocks. A lot of the boards have been compacted (unlike the ridiculously large boards in MP4) which almost brings it to the roots of the series. The board design, IMO, is by far the best in the series. The minigames are fun, and you can choose to play "skill games" or "all mini-games" etc.
In short, Mario Party 5 restored my faith in the series, took a step further, and I will do my best to try and forget the rotting dissapointment that was MP4.