I am all for in game voice chat for all mp games.
Here is why. I am a casual player, who doesnt really have the time or interest in clans or the like. I prefer to just hop into a game and play. Personally I really like how BF2142has their ingame voice chat.
Its simple. Make it a push to talk system, so that you can ONLY voice chat to your team. There would be an option in the setting menu to be able to hear voice chat or not (bf2142has this, I belive it it so people with slower connections dont have to revice the extra data).
In game removes the need for 3rd party apps like vent or TS. Haveing to set those up is a pain. And quite often it is imposible to set it up for a random group of pubbers who are only playing one match together.
I never understood why in built in voice chat never took off as an important feature.