[DGDobrev]

I did compare them - a russian friend of mine bought D3 and let me play for a while. King's bounty outweighs Disciples big time.

First of all, Disciples is wickedly unstable - at least 1 crash every hour. King's Bounty is very stable.
King's Bounty has minimal amount of bugs (even the russian version) - Disciples 3 is full of them. Abilities stop working, bonuses left unchecked by the game, hitpoints go way over the quota, and whatnot.
King's Bounty provides extremely interesting strategic battles where each move and each unit count. In Disciples 3 "He who controls the concentration spots wins the battle". Concentration spots are cells on the battlefield that let you deal double damage as long as a specific unit (melee, ranged, caster) stands on it.
King's bounty has over 50 units. In Disciples 3 there are no more than 40 (if you count the upgrades of the units, they are more than 50 as well).

So far it's safe to say that Disciples 3 is one great blunder. I agree that the game is beautiful, the unit images are very pretty, the units are well textured as well, but having the game crash every 5-6 battles (for various reasons) or so takes the fun out of it. Just read the russian forums about it... If I recall correctly, right now there is a mini "competition" who managed to play the most without a crash. So far one guy leads with 5 hours or so.

Akella and .dat have a lot of work to do to fix all the game irregularities they made. Right now Disciples 3 is by no means a worthy successor to Disciples 2.