Honestly, that's all you need. Once your flurries let you surpass the Fighter in number of attacks per round, you can constantly find yourself surrounded by prone opponents rising to their feet on their turn.
That, people trying to get away from the flanked position you put them in, and fighting while in rough terrain from a stable position when your opponents can't 5' adjust will all give you additional AoO's.
Not to mention it's a gateway feat to Hold the Line, Karmic Strike (iirc), and others.
Beside's, it's up against Deflect Arrows. Is it that difficult of a choice?