A true classic. Has aged very well.
The big flaw is of course the late game, which can be mired in managing every little piece of your civiilzation, reacting to every piece of your enemies' empires, and trying to find the motivation to care about dozens of little problems. This is especially bad when you are the clear winner you will find yourself trying to find an end to the game. You will find yourself leaving cities wasting their time because you don't care about them, concerned only with moving your army around (which is likely already big enough to win) or managing your best cities to finish producing large spaceship parts. [these represent the two types of victories - externally with armies or externally with researching and producing a spaceship to colonize alpha centauri].
This uncaring also leads to preferring to build wonders like Leonardo's workshop over something that might be more useful just because Leonardo's workshop means you don't have to painstakingly upgrade everything you own all the time.
There are other quibbles as well. Even if your map is round there is still an invisble edge that fools your units. The AI can be enraging too. It cheats to make up for it's stupidity and lack of foresight.
The game is simple, doesn't take up much space, doesn't need a disc and is very customizable especially if you dig into the hard drive files, which are labelled in such a way that they just beg to be recognized by the user and altered. Add units, change the rules, but always remember that the wrong changes can confuse the AI terribly.
The scenerios are fun, and making your own is fun too. You will have to play with the system a while to get a full experience out of it, but it's worth it. If you're creative you can do some interesting things.
I said the AI cheats, but if you forget about what's fair, the AI provides a formidable challenge if you play at the right setting. A lot of the time you will want to play an easier game, which is less thrilling but provides a soothing experience in its own right. Civilization on an easier setting, but not too easy, reminds me of computer solitare. It's a great time waster if you feel like brainlessly going through the motions or sandboxing a little.
This is getting a bit long so I will say that this game has many strengths over the newer civ games. It is a lot simpler but not "too simple" which I would accuse civilization 1 of being. Civilization 2 is one of my favorite games ever for sure.