Pros: Warm and clean sound; detailed; comfortable
Cons: Poor built quality
Design/durability: The earpieces' finish is good, and they do look stylish. However the built quality of the cable is very disappointing. I've successively had 3 early models of the SuperFi 5 (which all broke after a year of careful use), and although the cable doesn't tangle, it is very poorly made and cracks easily, leading to faulty contacts. Not built to last. At all.
Fit/comfort: Overall the SuperFi 5 are quite comfortable. The Comply foams are easier to use, since it is quite tricky to reach a good seal with the silicone tips. They are small and hold in the ear very well. Only downside is microphonics, unless worn over the ear.
Isolation: Very good, not much to say.
Sound: A nice surprise, especially for the price. The bass doesn't go very deep but is well defined and impactful. The mids are excellent, they sound lush and refined, vocals are very delightful to listen to. The highs are present, slightly "metallic sounding" but well articulated. Soundstage and imaging are better than expected, very 3D for the price. The overall finish of the sound is very coherent, with a slightly warm but clean signature, and great details.
Bottom line: Great sound for the price, but poor built quality kills it. I had them changed 3 times in 3 years. I've walked away since then, too bad I really liked them.
Ps. they've been renamed UE600 recently, sound is similar.
Here is the actual inside of one of my now-dead SuperFi 5 (faulty cable).