Eileen can overwhelm others with her speed and the number of moves she can perform.
The most notable feature is her Interrupt and Cancel actions that can be performed in the middle of a move.
This can be executed from a variety of positions, so it's no exaggeration to say that just knowing this can make a world of difference in the range of your attacks.
Although the damage of each attack is not high, the key is to use the Cancel action to put pressure on the opponent, then to aim for moves that induce stagger when guarded, or moves that start combos by counter-hitting.