For most, this will be a huge improvement as a case for cooling your components.http://www.anandtech.com/show/4648/rosewill-thor-v2-the-god-of-cooling-and-silence/5
It however should not be described as a quiet one. Even on low you are looking at 40db+, high it obviously starts to go up.
Sure their are worse out there and the case it self is not the only cause of noise (not in that test), but for most users, so it is something to consider.
If you are after quiet case, check the reviews and look into cases which can boast noise figures that is nearer to 30db or just replace the fans on a case you like that are designed to be really quiet nearer to 20db each.
Do I have a good suggestion for you. Not an exact one, I've always been a fan of Zalman for quiet tech, without knowing your specific needs that is all I can say.
It is an impressive case you'll like it. It could even be an improvement over the one you own for noise, but you'll also want to quiet down other parts of your PC with new heat sink+fan for processors, anti-vibration kits for loud hard disks etc.