Firstly, these have great sound, as you would expect for their RRP. They are in the same quality bracket as Sennheiser which is definitely a first for Creative headphones. The bass is very impressive, and doesn't dominate vocals, even faint whispers are clear. The bluetooth doesn't sound quite as good, I am presuming this is a bitrate limitation, but it works fine and is easy to set up.
The only real problem that stops these being perfect is the basic fit. The cans fall into a size that isn't quite big enough, or small enough. They sit awkwardly on my head and don't feel secure. There is also the problem of pressure; to make them feel more solid I make the fit tighter, which just gets sore after a while. Plus, they make my ears moist, which is never a good thing. Fit is obviously a personal thing, so I recommend you measure the internal size of these next to a comfortable set you already own.
Build quality is overall very good, not professional-level, but as good as you'll find in consumer kit. The mic is a bit of a letdown, and sounds no better than what you would get with a £20 Sennheiser headset.
Overall, sonically excellent, but (for me) ergonomically flawed. Try before you buy.