as a truly bilingual person, i can offer some information on the chinese voices which perhaps others cannot. mandarin was the first language i learned, and while english came more than ten years later, i hope you can see that i command it with somewhat adequate finesse.
it appears that the devs utilized 3-4 separate voice actors to do these, and they range from fluent speakers to those who are atrociously bad at spoken chinese. at least one, maybe two, of the actors speak flawless mandarin chinese, which is what you would hear from a real PLA soldier. unfortunately, these authentic phrases are the ones you are less likely to hear in game, such as various 'spotted' messages.
the next level down sounds like a cantonese speaker speaking mandarin. the pronunciation difference between cantonese and mandarin is so large such that northern and southern chinese people can not understand each other. so, even though the phrases are somewhat annoyingly mispronounced, they are still understandable. a lot of the battle status messages, commander orders, as well as the female voice announcer, fall into this category. this is perhaps not surprising, as a disproportionately large percentage of chinese immigrants and expatriates are from the southern, cantonese speaking regions, which have easy access to seaports and a historical penchant for exploration.
finally, there is at least one voice actor who sounds like he just took a semester of chinese in college and failed with flying colours. he speaks so badly that many of the lines are unintelligible to me, and it took quite a while [about a week] of playing before i finally figured out what he was uttering.
my biggest gripe: the problem in the voice authenticity is not the comedically inadequate pronunciation. a lot of the lines are grammatically incorrect, or are things you would never hear a real chinese person say. it's obvious that they were written by someone completely unfamiliar with chinese culture, with only a textbook understanding of the language [or maybe they just threw english phrases into babelfish]. worse yet, the military terms are almost unequivocally wrong. just one example off the top of my head. 'attack this position' is translated into 'attack this battlefield/battleground,' referring to the map as a whole. it would be the equivalent of an officer in iraq telling his troops to 'attack iraq.'
despite all the glaring errors and painful speaking voices, i'm glad to be able to hear my native tongue, however butchered, in a videogame. and yes, it is an advantage, albeit a very small one, to immediately know what is being said without having to look up at the console output.