I hate to be so equivocal on a game, you know?
I think, for me, I'm becoming increasingly overwhelmed by grand strategy games. There was a time when I grooved on them, but lately I find myself drawn to games with a tighter scope. For example, while I'm a huge fan of WitP:AE, I strongly prefer, now, a tighter focus on one strategic area. This is why I'm so interested in getting Uncommon Valor again. Similarly, while I'd like to play an entire campaign in Scourge of War, I have no real desire to zoom out to managing the entire war effort for the U.S. of C.S.A. Just a bit zoomed out...let me manage the Gettysburg campaign, but I don't want to manage all of the theaters around it.
It seems (I haven't played long enough) that Grand Tactician does allow for these battles to go on for multiple days. Theoretically that could increase the tactical scope over something like SoW. But it doesn't seem that there's an option to, say, play 1862 eastern theater only for example.
There is a layer between what GT is, and the tactical battles, that I wish existed...that pesky operational layer which is really where I feel most comfortable. It could be in GT, but if so I didn't come across it just yet.
For me the game is worth it just for the potential, but I'm a ACW fan. If the subject matter was WW2 or some obscure 19th century war, I'd be far less enthusiastic.