Much better that its predecessor
I played both Populous 1 and 2 and I found this second a much better designed game. I loved the tactics you must develop to win a match, this was missing in the first Populous. It's an upgraded version of Populous 1 under all aspects.
The background, greek gods, is simply well planned, it's always a pleasure to battle against Mars or Zeus himself!
I never heard of people who finished the game... it's an enjoyable game, but it takes too long to end. There are so many missions/levels to take that you'll become pretty tired.
The Bottom Line
A good game, try it, play it a few times and you can get addicted... but I dare you to play it to the end!