I definitely agree that a large part of the appeal of Warcraft is the setting, and also how polished it all is presented. Especially the voice acting of course, but also the creative way the buildings and units are designed. It’s just a pleasant world to be in, I think.
In terms of pure gameplay however, I must say I’m a bit disappointed. I’m at level 13 in the Human campaign now, and there’s only been 1 or 2 levels that posed any kind of challenge. I expected it to become more difficult near the end, but actually the last 2 levels turned out to be extremely simple. It’s all a matter of just building a big army and then overrunning the enemy. Because the AI lacks aggression, this strategy works on basically every map.
So all in all… it’s quite enjoyable to be around all these characters in this fantasy world, but it doesn’t seem to offer much in terms of actual strategy.