Great little add-on... but, makes the game MUCH longer also. My non-gamer friends love the add-on. I would rather play something else. So, my personal take is a 5, but the other five people rate it at about 8, so I gave it a 7.
While there are probably more interesting ways out there to expand Monopoly (thus the just above average score), this expansion fits and adapts nicely without changing too much of the original appeal of the gameplay. Fits nicely, even with our vintage Monopoly board. Adding the center game area mixes the game up just enough to spice up the strategy. Expansion gives players more opportunities to collect money, jackpots & tip the scales, plus introduces new properties including utilities. Now that we have the add on, I don't see why we wouldn't play without it.