Soulflay gives its user life and mana leech, although certainly useful for physical fighters, quite a few unique items have this trait, making Soulflay rather redundant. Soulflay does have potential for having a high mana leech, but otherwise it is not special in this aspect.
Perhaps the only thing worth noting on Soulflay is its slightly increased Attack Speed, as two-handed swords are typically slow. However, it is only a 10% increase, which is barely noticeable anyway.
Overall, in terms of unique swords, Soulflay does deal a good amount of damage when wielded with two hands.
One-Hand Damage: (8-10) To (20-24)
Two-Hand Damage: (22-26) To (51-60)
Required Level: 19
Required Strength: 47
Sword Class - Normal Attack Speed
+70-100% Enhanced Damage
+10% Increased Attack Speed
4% Life stolen per hit
4-10% Mana stolen per hit
All Resistances +5