I don't like HoMM 5 because of its over//complicated graphics and other reasons. I have both the 3rd and 5th parts installed. Just thinking about how long it takes to load the 5th one gives me same-shivers, so I just click my mouse on the 3rd part.
My buddies and I love playing the 3rd one "hot seat" style. And imagine how long you'd have to wait for loading and reloading if you played the 5th one. Besides, everything is more abstract and simpler in the 3rd part.
Generally, we love to get creative with hot seat. We take a large map (specifically Apocalypse), edit them on equal terms (the opponent and we have equal chances + all artifacts), divide into teams, and go for it. Right now we've set creature growth only for level 7 (i.e., weekly growth of about 23 creatures) — and let me tell you, it becomes a total bloodbath...
With this kind of gameplay, we don't even think about the 5th part...