With every new HOMM title I recognize how good the predecessor was. Nr. 6 is definitely the worst of the series.
My review consists of all addons up today, so I´m considering the game as a whole.
Nr. 6 started stripped of everything. A ridiculous puny game with tons of bugs, glitches and only five races. A true disaster. Ubisoft managed to bring the game into quite playable condition in updating it with dozens of patches (nearly 2 gigabytes...). The game is still buggy. Objects disappear from the map and several areas remain unpassable and buildings unaccessable.
The only thing truly done well is the graphics and animations. Also the short waiting times between the turns (which were a great pain by HOMM 5) are a blessing. Further I appreciate the return of the previous town portal spell. However the rest is a bad experiment with the gameplay.
The campaign and maps are one huge boredom. Designed nicely, however uninspired. Lacking buildings and improvements where they should be, the monster variability is very poor, everything seems placed random by computer and not by human hand. After I´ve defeated the 20th skeleton spearman in a row I begun to ask why I´m doing this to myself.
The boredom and lack of creativity in campaigns is compensated by extreme difficulty. The story varies from miserable to ridiculous and your only way out is to design your own map (or download one from internet).
And here is another problem. You cannot edit the campaign or the given scenario maps by yourself due to some strange reason. You may only edit the downloaded maps. Allright, let´s take a look. I remember the map editor from HOMM 5. It was not well designed and not easy to handle, but after a time one could get used to it - provided it hasn´t crashed or frozen. The HOMM 6 editor is a different story. Putting it into few words: it reminds more of a torture tool and the team who has designed it deserves a slow and painful death.
Another fact which backfires is the hero development. It reminds me quite of Dicsciples 3, however by far not that well working. Now the heroes of one faction are pretty the same, divided into might and magic classes. You miss many useful skills like logistics, war machines, wisdom and you miss also all the thrill leveling your hero and looking for witch huts or skill libraries. Also ballista and healing tent are gone - just another victims of the "stripping of" measure.
The AI is the worst of all series and behaves truly idiotic. When fighting the neutral armies the battles are repetitive and about the same mouse clicking (another deja vu from Disciples 3), the fights against the AI players are beyond frustration. When the AI decides it is too weak (which it does in most cases), it simply flees from the battlefield. So your new objective becomes chasing fleeing heroes across the map and ending every battle withing just seconds of the first turn.
The summary - HOMM 6 brings no pleasure. Instead of it lots of boredom, repetitiveness and annoyance. More than its predecessors ever did. In case you have HOMM 6 and want to buy Shades of Darkness, don´t do it. This addon is more terrible than it looks (even it brings few new maps and a new faction) and the game is better without it.
At last I sincerely hope, this is the end of the series. To all game exploiters and money squeezers: Better cut off your hands, before you unleash another painful sequel. Just let the series rest in peace.