I have played HotW about 6 times and have found it to be very enjoyabe.
It typically takes about 4-5 hours of time and yes the comments of power differences between the varios civilizations can be extreme, which is why I feel that game is balanced for 6 people and starts to skew rapidly the less players you have.
For example, there is the pre-cusors to the Mongols (forgot their names) who give you 6 armies and no capitol on worthless land during the same age that you can draw the Romans (I think)
Additionally, you with fewer players, it is possible for a player to camp in an area and just collect points - whereas other players are beating the stuffing out of eachother. (Classic example was that I drew the first 3 chineses civs and was able to take over china, Japan and India - whereas my two competitors kept drawing European civs - so they would fight eachother)
However, that being said, I have found it to play pretty close to historically - the civilaization arder does a great deal for this. For example in the last age you have the rise of the Dutch, followed by France and England taking most of thier colonies - again very accurate.
So if you have the $50 to throw down, I would recommend it - plus the plastic pieces are very enjoyable (and can double as marauding hummanoids in your D&D game)