Earuto said:
PM1 had a better gameplay.
PM2 had a better storyline.
PM3 had a lot of thing I didn't like.
PM1 was classic, but frankly, I don't see where you're getting the "better gameplay" idea. After all, while the PM1 system worked really well, PM2 improved on it in so many ways it's not even funny. If the audience system, partner HP, paper curses, and limitless number of badges didn't get your attention, I dunno what will.
Besides its soundtrack. PM1 had a few really good tracks, but PM2 has hits all throughout the game. If you ask me, a good portion of its soundtrack is just beautifully composed. It surprises me that Nintendo didn't sell CDs of the soundtrack, because this is definitely worth ripping onto your computer, even if just to listen to it once.
To be honest, I liked PM3's storyline just as much as PM2's. It's also fairly significant because it's the darkest plot to appear in any Mario game to date. The end of all worlds? You don't see that in Mario Party.
I do highly agree that PM3 is levels below its predecessors. The 100 pit(s) of trials is plenty fun, but otherwise, the difficulty of the game as a whole is just abysmal. Not only is the badge system completely removed, but the bosses are pathetic, and you don't get to choose how you level up - the game does it for you automatically. And, to be honest, I think the dimension-flipping should have been skipped. It's a really cheap way of avoiding fights and only really comes to good use in a few levels. Soundtrack has the same feel as PM2, but it still just doesn't compare.
So, yeah, those are my two cents.