Open Source + Awesomeness= Great Classic!
So, i say it's a good game to play, and some new additions to game, (New AI, still in the BETA version 2.0) makes the game even more promising for the future.
The thing is: The timer takes away some of the fun...
Another good thing is the artillery assignment to a sensor, allowing it to fire with help from the sensor. That comes in handy when attacking or defending (although defense with indirect fire isn't THAT effective, IMHO)
About the multiplayer, it has some fun things, like the super-heavy bodies (won't spoil them here! :D) and the fortresses. (BIG fire power, i can tell you that.)
Last but not the least, the weapons. The wide arsenal in Warzone 2100 allows for different strategies for the same situation, using different weapons. Need to shred Cyborgs? Assault Guns will do just fine. Tanks in the way? Just blow'em with the Heavy Cannons or with AT rockets!
So, you've got to try it. I think this was one of the best games out there i've played, although it won't compare to a generals or Red Alert 2. Then again, they are different concepts, though.