Well, I didn't vote since I never played the other Moos, and it would be hard to recommend it to someone since it DOES have such a steep learning curve--which is only worse with the 1.25 patch since the manual becomes completely outdated...
That said, the game can be quite addictive IF you can get into the spirit of it. You are supposed to be the Galactic Emporer and NOT some micromanager who decides everything about every planet. If you can accept that role, you can like the game. I guess the closest thing in Civ terms is, if you can play Civ with the Governors on, using whatever units or structures they build with workers set on auto, with you only dealing with the combat units and battles and diplomacy, then you have a chance of liking Moo3.
The problem is, though, that you say, OK, I won't micromanage, but then you get overwhelmed because you realize that the choices you make on macroscale sliders DO have Empire-wide effects! If you've never played before, you might figure out what putting one DEA in a region of one planet does--it's understandable--but until you've read all the posts on the Atari MOO forum and played the game a bunch of times, you really don't know what your Empire wide slider setting is gonna do--and you can get paralyzed with indecision.
Stick with it, though, and when it all 'comes together' it's easy to play!
You MUST, however, play with the Senate victory On. Since the AI is STILL not very good (although it's much stronger with the patch) you'll be able to beat it on any difficulty level. You need the Senate victory On for a few reasons:
1) The game will end somewhere between turn 200-300. Your goal becomes to make sure you get in the Senate if you don't start in it, STAY in the Senate if you begin in it--which can actually be quite difficult! As such, this DOES make the game a challenge since you must stay focused on that objective and can't lollygag around.
2) If you DON'T use the Senate victory, as you get farther into the game, the numbers for the Empire will get huge--and there are many roll-over errors in the game where too large a positive number causes it to go negative with sometimes very dire results!
3) Since the game will be ending in that short time frame, you will NOT get all the techs and so may have to develop different tactics and learn to use what you have instead of waiting for stellar converters. (Which I've NEVER gotten and win without!)
So, again, you can see I'm mixed on it--I can't truly recommend a game with some game-killing bugs...
And now a short word about mods. Go to Atari Moo and you'll find mods, lots and lots of mods! On the original release I had installed the tech slow-down mod, but since the patch I've played it clean. I guess after a couple more games I WILL go and figure out which mod(s) I need to make it a challenge--perhaps the Invader megamod mentioned on this board. but there too many to choose from it makes it hard to know which one--or combination of them--to use!
