My opinion after 40 played hours
This game is IMHO worth playing for everyone who played older games some years ago. Even if you don't spend a single penny on it you still get a lot of fun. Campaign is playable without paying as well as skirmish against your friends. There is a option to disable gear so it is like standard strategy game.
After 25 hours I've bought Pro civilization pack for 10€. But I don't consider it as a necessary. Regular PvP is possible to play in "Champion mode" which means that all gear and other stuff is disables so no one has any advantage over you. Except skill :D
Skirmish is just a mess without skirmish pack. It's completely random (enemy's strategy, starting resources etc).
Let's wrap it up. The game after 40 hours still entertain me that is something I cannot say about most of my games... Even without spending money there is a long campaign and option to challenge your friends. Also 10€ is worth it for so many hours of strategy entertainment..