I really liked Mario Party 4, but the fifth game in the series never set right with me. I'm glad it was just a rental.
Granted it wasn't drastically different from the 4 previous titles. You still move on a game-board and play mini-games.
Some of which were fun, others were kinda dumb.
The game-boards were too oddly designed as well, and the points to win changed very drastically. It was almost like mini-game victories made a little difference as long as your luck on the game-board improved. So after 5 I was never motivated to get any other game in the series.