I'd venture to say that Disciples 3 is terrible.
The only thing I enjoyed about the game were the graphics. The camera moves freely both in and out of combat, the world is well-drawn and well-made. But this is where all the good news about the game actually end.
The bad news:
1. Out of the box version had a swarm of bugs. Most of them have been corrected, but there are still a number of bugs that persist.
2. Winning battles was easy as pie, even on the highest difficulties - control the focus points (double damage) = win the battle. No challenge at all.
3. With good items you can destroy a capital with low-level troops. Capitals are also much, much easier to capture than Disc2.
4. AI rod planters could pass through enemies, capturing resources (might have been fixed). This puts you at a terrible disadvantage - you may well encounter a well built and leveled up army at your gates while you're still eeking a meager living trying to beat some nearby resource guardians.
5. 3 races, more to be added in the expansion. Nice. We have to pay for extra races as well
I can go on, but I think that pretty much covers it. KB has much better gameplay and the battles are much more decisive than Disc3.