First, I'd like to have a "neutral" rating - this game is too good, for all the things it does well, to have a negative rec. But it has two serious conceptual flaws, in my opinion, that I want to bring to light.
First and most important, all the details you can keep an eye on make it slow like heck. If you play carefully, making sure that no unit is slacking, not rushing combat etc., there will be hours until you see who you're exactly opposed to. Even then, you're probably far from making anything but the most basic, generic units, available to anyone.
Secondly, since it is all about (very) long term planning, you'll probably do well to start gathering all kinds of resources early on. However there's quite a lot of different resources, so it will take a lot of work to capture all the mines, farms, lairs, and that includes ones that you have no idea if they will ever see any use.
In short - if you can't commit serious time to this game, there's just no sense trying it.