Great PSU, nearly silent and probably quieter than anything else in your machine. The cables are neatly wrapped in techflex and it has a nice, no-nonsense black finish. The only problem (and it's not really a problem) is that you need to put a bit of effort into bundling the extra cables you don't need out of the way and not blocking the psu's fan.
Designed, no. Manufactured, yes. Although technically Seasonic arranged the platform, the specific components used and overall quality of construction is dictated by Corsair, which is the reason it's such a great PSU. There's a big difference between the cheaper Seasonic units such as those sold under Antec's name and the high-end ones made for Corsair (the cheap ones are still good, but Corsair's are significantly better).