Fairly loud, but it varries greatly on many factors.
When I have my CPU fan cranked up I don't hear any of the other fans, although that is loud as hell
If you use the stock case fans and connect them up to the speed controls then they aren't all that loud, although they put out more noise then a 'standard' PC for sure. I have replaced three of the stock fans in my case with louder fans(lit, nothing was wrong with the ones that came with them) and even when they are turned all the way up and my CPU fan is all the way down it isn't unbearable. Overall I just leave my case fans all cranked up, my processor fan makes them fairly inaudible.
The fan controls make a
huge difference on my processor fan. When it is spun all the way up(5400RPMs) they thing screams, down to the lowest setting it isn't offensive at all to me. Temps in the case depend hugely what you are running. I have dual 7200RPM fans, a decently OCd AXP a GF4 and a really hot running sound card(!?) that throw a decent amount of heat but even then I turn the case fans down all the way there is no large spike in temps.
If noise is a big concern for you, I would not reccomend the case. Considering what it is though, it isn't all that bad.
Honestly speaking, the weight of the case was a much bigger shock to me then the noise. I have the V1000A(black one) and it weighs significantly more then a standard case, the size of it is also much larger then what I thought it would be. Not saying these are bad things, although the case is so large it wouldn't fit in my desk where standard cases have plenty of room.