Heroes VI is overall a good game, you can like it if you are patient.

I played the campaigns on hard difficulty and my review is based upon complete edition with every dlc - addon possible.

Lets start with the worst part - Bugs.
Game is old and out of support. Even when it was in support it had many bugs it seems, some of them still stands. I was able to run it fullscreen, suddenly i wasn't able to. Now i play in windowed mode.

There is a bug that caused 5th dynasty trait to be re-locked. Couldn't find any solution. -> https://forums.ubi.com/showthread.php/1834980-5th-Dynasty-trait-re-locked/ we are waiting a fix.

Some talents have issues sometimes. For example if your creature gets another bonus action because of cleave, with a retaliation strike, it cant use it. These are more likely design oversights but still sometimes annoying.

Graphics are quite fine, animations are lovable, maps are detailed.

Sound: Music and sounds are very good like any Heroes this somehow never fails.

Story and Writing : Childish at best. Some dialogues does not make sense at all, you will have a hard time understanding what is going on with the campaign.

Hero Balance Might vs Magic : The worst in the series of Heroes was magic being always powerful, not here, no sir. There are some seemingly imbalanced skills like time statis but in the long run a might hero can get so many options i can easily say they are perfectly balanced.
Many web sites and reviews about the game are based on old versions which are not tweaked so don't rely on them.
For example you can see people whining about "chilled" giving fire vulnerability , it gives might damage vulnerability now, so as a Sanctuary hero for example it makes sense.

Hero variations, Tear Blood rep system.
This is a new and a very good system in my opinion. During your adventures, your main hero makes some choices usually around empathy (tears) or cruelty/getting things done? (blood) . Much like Mass Effect Paragon / Renegade system.
For most common example , you overpower creatures and they run , right? Pursue them ( blood) let them run ( tears) . Oh you get exp both ways btw.

All talents have 3 innate reputation. Tears,Neutral,Blood. Once you have a reputation level, any talent with the same reputation becomes stronger.
For example if you get Might Defense Lvl 1 - it normally adds 1 defense. If you are a tears-I hero, it adds 2 instead. And if you are tears-II it adds 3 instead.
Like this, all talents improve if you align yourself accordingly. Offensive powers become stronger when your hero is blood vice versa.

Since combat rarely tooks more than 6-7 rounds, unless you try to overachieve, you can use 3-4 active skills ( spells and might abilities) rest should be passive.
Every hero can learn might and magic skills, but only might heroes reach Tier 3 skills and only magic heroes can reach tier 3 magic skills. Spell schools are also related to your hero type. Inferno heroes cannot Learn water magic Necromancers cannot learn light.

There isnt many useless skills but some are better than rest.
This is still the best heroes i ever played ( havent played 7) but because of bugs , hard to recommend. I am old and computer engineer, i am resilient against such things :D

My heroes order for curious . 6 >5 >3>2>1>4. ( 3 is loved because nostalgia, magic was overpowered ,earth especially, graphics are bad/old, lots of useless skills, random hero building...etc.)