I personally am not fussed about the lack of out-of-game chat. If the server crashes, I go do other things. I really can't say I ever get into fights with mega lag bombs that kick me off but leaving the server going.
I've used it, works fine. Nice thing is that when you setup gangs you can do everything in game and get the command channels setup, etc. Plus you can see who is talking (in the chat window and an icon over their ship too I believe), which is nicer than using a teamspeak overlay or somesuch. It's cheap too.
Oh yah, and it works with anyone that has it - you don't have to give "random group person 18" your TS info.
Bucket o'suck if you've already got an alliance TS or Ventrilo server. Doesn't do anything they don't do, can't have a command channel across multiple gangs, and until nearly everyone is paying the extra for it, completely useless.
There are things I can think of to improve on TS/Ventrilo, however very little that I can think of specifically for an in-game system that they couldn't do.
The Eve voice thing is *really* being pushed with the revised fleet system that CCP have been blogging about. Someone on GF rightly commented that it looks like a (much-needed) change to fleet management that is in fact being driven by the need to get people to buy the damned voice service.
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