Edit: How the heck did I end up posting this in the wrong thread?
I don't see a way of deleting this to fix my mistake either. Welp, might as well fix it by contributing to this thread properly. 
GC2 has definitely taken up a lot of my time in the past. Its a good game, but there were a few things I didn't like about it. Specifically the way the combat worked. Combat in GC2 isn't like traditional 4x games where you move a unit over to attack another unit. Its all automated and resolved behind the scenes mathematically and then you see a graphical representation (ships firing at each other) of the outcome of that math. There are variables so reloading a save and trying the same combat sequence again can give different results, but for the most part its not to overwhelmingly different.
Starbases were also completely useless for anything other than an econ bonus or influence bonus. It was pointless to even try to upgrade their defenses since the AI would never attack them unless they knew they could blow it up, and that was very very easy to do by early mid game. Heck, even 1 ship with 45 HP worth of fire power (pretty easy to get) would 1 shot a fully upgraded starbase.
Building asteroid bases was also very pointless and extremely time consuming. If there was one mechanic I could change it would be to get rid of the distance penalty in favor of having a freighter being required to ferry the ore back to the designated planet.
What I absolutely loved about GC2, however, was the different methods you could use to build your planets up. There wasn't one set way you could win. There where all kinds of methods. All econ, all factory, all tech, or a mix of whatever worked for you. They each had their advantages and weaknesses. The AI was also very smart about how it reacted to your moves. I remember the first time I went to invade an enemy territory. The obvious method of placing my ships around their planets and declaring war didn't work because the AI knew what I was doing. It totally threw me off because I've never seen a game where it was able to predict that move. Whats even more mind blowing is the AI contacted me and it TOLD me it knew what I was doing! 4x games are notorious for falling for that move. Build up large forces at the border or outside the cities, declare war, and crush them in 1-2 moves. GC2 doesn't let you do that (unless you massively out tech them) because it knows this trick and builds viable counter measures, or goes to war with you prematurely so it can destroy your fleets before you've had a chance to build up. I actually have to think about my strategies if I wanted to win in a conquest game.
The special structures and buildings also do neat things for your economy and military strength. I like how you have to space your super structures out among several planets instead of hoarding them at one well protected planet. If you try to do this it actually hinders your economy.
Over all I'd say GC2 is worth dropping $30 for the Ultimate Edition which contains all the expansions. Its definitely fun and I'd say the strongest part of this game is its AI. This game can actually be a real challenge. Not "OMG this game cheats!" kind of challenge, but an actual honest to goodness challenge.