I was talking to some of the Fantasy Flight employees at Gen Con this last year when I was demoing the game. They removed both the Skavens and the Wood Elves from the demonstration. They mentioned that all the teams were balanced when playing a regular length game as described in the rules of play. When playing a shorter game (as we did at Gen Con), the Skavens had a slight advantage (only winning 10-15% more), while the Wood Elves were weaker. They mentioned the reverse was true when playing longer games.
it's funny, i played my wife after reading this in the forums, she chose Wood Elves, and I picked Skaven. Her first game ever(and mine, but i'm a rules *****, and i do my research before ever playing games), and she kicked my ass… Not sure why Wood Elves are considered weak in 2 player, i think they seem quite strong….
However, Humans i feel are particularly strong in their all-roundedness… Yes, their blitzers are amazing, but the fact that they usually have a player in hand that can do what needs to be done to get or keep the upper hand is really strong. I've struggled the most with Dwarves, although that being said i won my first 4 player game as Dwarves, but i was behind up until the last turn, and a few end game fan points just pushed me over the line (we were playing WITH Salary Caps).
All that said and done though, i really am impressed with generally speaking, how well rounded everyone is. No matte what race I am, and what race ui'm up against, there's always something to be aware/afraid of, or a card you hope they don't have.
Even though i've only recently got this game, i'm dieing for an expansion!