Interesting at first but then it gets disappointing
It is these things that will provide interesting and draw you in if you have played total war before. It will feel refreshing that there is a new take on the old total war concept. Being able to equip your heroes and assign them skills was something that I found to be very interesting. In total war, most of the time, the traits and stats of your heroes were generated randomly while here, you can actually choose what skills and stats you want for your hero.
The adventure quests on the other hand provide something interesting, depending on your choices, you get to gain/lose things like gold, reputation (you can recruit certain units and gain certain skills depending on your reputation - both good or bad), even the choice of battle. so you can do an adventure quest with a possibility of battle and actually avoid doing battle with the choices you make in the quest.
However, these new things only prove interesting at the start, later on the game you will notice its lack of depth. Armies, for example, you can only take control of a very small amount of armies, you only start with one army (the main hero) and at the end of the campaign you can only take a maximum of 3. So no matter you got this abundance of heroes, you can only send out one army with a limited number of heroes (only 3 max per army), and a limited number of troops.
Then there is town management and economy. Your towns can only produce like at most 4 buildings (and most of which you can only build one particular building and then its upgrade). Economy is nearly non existent. While you need gold to hire armies and build things, you can only get gold by doing battle and sometimes a one time gold gain from occupying a new town. So not really much to it, fight and earn gold to buy new units, build buildings.
Diplomacy as well turned out disappointing. While there is no longer a need to hire a diplomat to go to your neighbors lands to initiate diplomacy, the diplomacy options are lacking. Turns out you can only initiate diplomacy with a fixed number of neighbors and depending on how far you are in the story. In the prologue campaign, I had wanted to avoid battling with the smaller neighbors and just have an alliance with them so I could save my troops for the much bigger battles ahead but found out that there was no diplomacy option on them so I had no choice but to attack them and lost a number of soldiers in the process (i.e. wasted gold to retrain/rehire units).
Disappointing but from the point of view of the game developer, these things are necessary to delay the progress of the game and to keep game-play longer. In short, these limitations were designed as such to prolong the game experience.
So until the next total war comes out, this might be enough to satisfy you until you finish and then ask yourself "that's it?"