A enjoyable game that unfortunately in the end is marred by a massively lackluster AI and far too many bugs to count.
If you happen to be lucky enough to not have that issue or you've fully patched the game to 1.06 which takes care of that problem, the game itself is actually fun.
Changed from Disciples II is the battle or "arena" map as it were, instead of the old stationary battle map. You now have a maneuverable hex map to use, similar to Kings Bounty. Whether or not this is an improvement depends heavily on you're tastes.
I consider it to be fairly even with the last game, it's not a heavy improvement but it does change the flow of battles. Especially since they added magical, melee and ranged focus points to the maps at random. Which has the unit standing on them deal 2x of whatever style of damage it uses if it stands on the requisite square.
As a consequence battles are longer than they were in Disciples II in general, there are exceptions. This is mainly due to positioning of units, which some may find tedious and others may not. Unlike the old D2 in D3 the first few turns of a battle are almost nothing but unit positioning.
Sending your melee units out to sit and defend on focus points, or to lock up the AI melee units, or rush their back line. As well as sending your ranged/magic units to find focus points if they happen to appear on that particular map.
To be honest, later in the maps when your units have grown in strength. When encountering most trash mobs you will find the "quick battle" option to be your best friend. It is simply not worth two or so turns of positioning just to kill off some orcs and spiders.
However power creep is common to all games of this style, so it in itself is not a huge concern.
The artwork in D3 is beautiful, although the D2 community might lynch me for it I would venture to say it is superior to D2. All the unit artwork is very detailed, and the 3D representations of the units also look quite nice. Which is one of the things D3 has going for it, good artwork, graphics and atmosphere.
One of the downsides to D3 is the decided lack of factions. Instead of bringing all the old factions into D3 the undead and mountain clans were left out. Not that a whole lot of people care about the mountain clans, but still its a oversight that hurts the game. So basically you're left with the empire the legions of the damned and the elves. But if one of your favorite factions from D2 happened to be one of the missing two its going to put a damper on the game for you.
Some other things that were changed for instance was D2's absolutely abhorred terrain capturing mechanic. Thank the gods that gone are the squishy death magnet rod bearing generals from D2, as well as rods in general.
They've been replaced with a "guardian" system. You have nodes by resources on maps that can be captured by any general. And instead of a rod you have a guardian of a type depending upon the faction, left behind to guard it. This guardian grows stronger with the passing of turns. Meaning the longer you let a certain node remain in the hands of the enemy faction the harder it will be to take for yourself and vice versa.
However, the main issues that bring this game down from being a fully worthy successor to D2 are its myriad of bugs even after a 6 month time frame between the Russian and US releases as well as patching up to version 1.06.
Just some of the bugs outlined, sometimes during a game when you try to build in your capital you will instead be thrown into the enemy capital(most notably the elvish capital). Which means building or recruiting units is impossible until you save and reload. Not a huge game breaking bug, but still it should not be there after 6 months and patches.
Another bug is the ability for your leader to completely fill his unit roster even if he doesn't have the requisite leadership number by dropping a unit on another unit they will both "transfer" to your party from your capital. This is also possible with your capital guardian, which is complete cheese.
On top of the myriad of bugs most of which I won't bother to list. Is the terrible AI. In battle the AI seems to send its melee rushing at you, but they will also attack the nearest target. Meaning if you put a summon in your way you can block them up for a few turns, and either punish them with range or magic or send your melee after their back line.
Also the AI's back archers and single target magic users seem to target your units at random, they'l be beating on your healer for half a match only to switch to bombarding your knight for no apparent reason. Thankfully the AI can and does make use of focus points, but still with its lackluster integration it barely makes a difference.
If you can handle the sub par AI, and the amount of bugs until more patches are released than D3 is actually quite enjoyable even if it doesn't fully live up to its predecessor.