There's two ways of viewing this product, the first is that it's an inexpensive set of bluetooth headphones, which are pretty comfortable, have great battery life, decent enough sound quality and work great with the iPhone 4. So for me, wearing this outside for walks / runs to listen to music is great, the bluetooth works great, never had any drops in audio, and being able to change track, pause, volume control on the device is so much more convenient than playing with a touch screen.
The second way (the bad points), is that they do feel cheap, the audio quality is good (not great), the headphones lack any kind of form factor adjustments. These are all fine to me thanks to the price. The only deal breaker, which thankfully doesn't apply to me, depends on how you use these headphones. Now this may be inherent to all bluetooth headsets, or maybe the fault of these headphones, but there's lag. Probably <500ms lag between the device playing the sound and the headphones blurting them to my ear. This makes watching videos on my laptop and iPhone painful (especially if people are visibly talking), but if it's just music you're interested in, for the price I'd say this is definitely a good product to go for.