HotA adds tons of new content: new towns, new artifacts, new heroes, new campaigns, new editors.. Yet everything blends seamlessly into the original. Graphics are not only extremely well polished, they also match the original style so well that they are pretty much undistinguishable from the rest. Gameplay wise, new towns bring interesting mechanics (no pun intended), but without going overboard. It still very much feels and plays like Heroes III. Respect for the original material + high quality content are the reasons this mod is so popular. Believe me, you don't want to skip on that one.
You need to go through a painful process of trail/error, tweaking differents compatibility options, just to be able to launch the game. And when you finally succeed, it runs so slow that it is unplayable.
