Your game crashes your voice crashes. ie no way of telling people youve dropped connection etc.
Its quality isnt that bad when a small group uses it - it gets worse as the users increase in numbers (Ive had it good with 50 or so and under on it in fleet work back in my FW days but more and it was nasty).
Its also cheap (ie part of the client, which means no other expenses to people playing for voice hosting, yes there is free hosting methods out there, but they arent the best solution really, and can easily mess up over night).
Also - no need to talk tech newbs through setup, connection and so on - its all quite easily done from the audio menu in game.
