Really the only game that was a horrific butchery on the series was Homm4, I mean the horrible town system, the horrible pick and choose monsters, the fact it changed from cities to "Order, chaos, death, life" and other generic crap if I wanted that I'd play lord of magic, at least they tied it in properly to the races. The only good thing in that game was the storyline, and it wasn't worth playing through for.
There are many things I dislike in HoMM4, but the magic/town system - or, rather the idea of it - ain't one. It's executed consistently throughout the game.
Now, if you said bad balancing, ugly isometric graphic style, Necropolis/Inferno merger, lack of unit variety in your armies, ...
And I'll be the vocal minority in that I liked H6, and am quite excited to see where it will go after the obvious two expansion packs when we have more than
five towns (lol). The obvious huge blunder is the always-online DRM, it's just that godawful. It also has a bit of a pacing problem. Dynasty System is kind of unneeded but doesn't exactly destroy the game, if you dislike it you can disable it for your skirmishes. But it is a worthy successor in my eyes, and a good Heroes.
Also, did someone mention H5's derpiest AI of them all that takes anywhere from five minutes upwards for a turn come late game and larger maps? Thankfully there is an AI patch that makes it quite a bit faster and not quite as dumb.
The defense rests.
/e: Ah, while we are at it, I presume that everyone of us didn't refuse to outright play both the third and the fifth part. What faction/hero spec do you prefer, and how do you do the skilling?
Personally, I either go for a) light-magic wielding knights or b) magical masters of Blowing Stuff Up. H5's Firetrap is the best spell ever.