Pros: Size (easy seal + comfort), detailed highs, isolation
Cons: Non-detachable cable
First off, these are ridiculously small for having dual armatures. UE's bundled silicone (gel-like?) tips are a very good match with these earphones - they have thicker than average flanges but are very flexible.
What the tips and size add up to is an instant seal consisting of popping them in your ears, pushing them in once, and looping the cable over your ear in all of 5 seconds. Their isolation is quite good, about on par with Shure's lineup.
The first thing to be noticed about their sound is their highs - quite transparent and very detailed. Mids are quite smooth but nothing too special. What surprised me was their bass response, which has a pronounced impact and good speed.
My one big gripe with these is the lack of a detachable cable. The stock cable is moderately thick, flexible, and virtually microphonics-free, but the stress relief and build of the straight jack leaves something to be desired. A change on these to the TF10/Custom UE removable cables would do wonders.
I got these back in the summer for ~160CAD (retail was 200-230) , but UE seems to have lowered their retail to 150, which really makes them a stellar value, if you can tolerate their cable...