Pros: The looks, Build, Customizability
Cons: A few sound flaws.
I love the look of Sleek's sa1, the rosewood body of them and the overall build quality is unsurpassed at their price. That is enough in a lot of people's eyes to convince them, they do, however, have a few problems.
The sleek customizability is not one of them though. They come with quite an array of tips of several types as well as sizes and two tuning filters. You may argue that the whole system is superfluous and whether someone can tune the sound to their liking is up to the user, but it is hardly a hindrance of them. When I got these I was going through a bit of a down-tempo electronica phase (bonobo, bluefoot project, shazam, cut copy, etc), so I went with the bassier port and small dual flange tips.
What I got was plenty of bass, mids that were quite good and recessed highs. With the other port I got harsh highs which distracted from the rest of the sound so that wasn't the one for me and I switched them out soon. Sound-stage of these tiny (6mm) drivers is quite impressive and wider than a lot of other iem's i've heard (for the price). Separation is also good and it's easy to get lost in the music with the good isolation they provide.
What is lacking in my opinion is clarity and detail. It's not bad by any means but there are a lot of earphones in/near the price range of these and several do it better.
Would I recommend them? Well, at retail price, buy them if you love the look, you should find a sound you like and they will serve you well, they are also built like mini tanks. If the looks don't bother you there are better out there so wait till they're on a special offer.