Warlock is more of a PVE interest.
You can spend a great deal of effort surviving the map itself. It's fairly entertaining, but also a frustrating game. Your champion units are extremely important to hold onto, but losing them is relatively easy thanks to critical hits. Once you jump the difficulty up high enough that the game becomes challenging, it's a real pain in the ass to keep things like wizards alive.
You don't have to grind though. The AI isn't any more successful at conquering the powerful areas than you are, if you ignore them and go straight for the jugular, you can take them out pretty efficiently. Even sieging the capital cities isn't that difficult.
I probably put 30-40 hours in it after I figured out how to play, aside from some mutliplayer games I occasionally play with another guy that likes it. Considering the cost of the game, it's definitely worth it if you like TBS.