Build quality seems good but not great. However, RHA does offer a three-year warranty on these guys, which is a couple of years longer than what you get with most headphones.
As for their sound, these headphones are more bound to please audiophile types who prefer well-balanced sound that doesn't accentuate the treble or bass. The SA950is offer smooth, clean sound, with good bass, but they're not incredibly detailed nor do they deliver incredibly deep, powerful bass despite their 40mm drivers. Speakerphone performance was fine.
The RHA SA950i is an all-around solid on-ear model that offers decent sound for the money. I can't say they excel in any one area (design, comfort, or performance), but they're lightweight and likable. I'd like to see them come in under $50, especially with all the competition in the $60-$80 price range, but the SA950i certainly holds its own soundwise with other headphones in its price class -- and it comes equipped with an inline remote and microphone.