This is a rare flawed gem, sadly hated too much to be objectively judged. If you don't buy into the mindless flame game, you'll find a pretty unique (if unpolished) game of rather well-executed macro-managemnt; certainly, we have Distant Worlds now, but all the way back then there was nothing. MOO3 was a bold pioneer into the lands unknown, and was stomped by angry fans by not copying the original formula. It's much less casual than the original. It requires some analytical skills and some effort to get into. But as soon as you adjust your mind, you'll be surprised how rich your game experience is.
And yes, it's 4 star rating for game with fan-mods, which add a much-needed polish. Don't even try playing without them. Seriously. Don't.