It's a great and very unique aproach on a Dungeons & Dragons campaign setting. Birthright is one of the most unknown and underrated campaign settings in the entire history of D&D. In a single game, you can experience kingdom management, quests, leading an adventuring party through exciting dungeon raids, commanding armies in battles, and even controlling a character with godlike powers.
I played and replayed the game back since 1998.
From my experience, the game is very fun but also challenging, depending on the choices we make.
I want to play it again on GOG because since then, I have played many similar games, but none have combined all the elements that this one does. And most importantly, no other game, DLC, or mod has ever returned to the Birthright campaign setting (as far as I know).