It's such a shame the mic is poor because, in other respects, the F1s behaved themselves perfectly: I paired them with a number of different phones and Bluetooth MP3 players and found that they linked up every time. The range was pretty good, too, allowing me to walk several metres away from the various devices before the signal began to break up. The F1s are even available in a bundle with an iPod-compatible TX transmitter, which clips onto the base of the ubiquitous digital audio player for instant wire-free music. It's an extra £28, though.
Sound quality isn't earth-shattering, but despite being completely lacking in bass, the F1s are surprisingly easy on the ears. Potent volume levels, an open mid-range and reasonably crisp high notes combine to make up for the weedy low end, and if you listen to a lot of acoustic music, as I do, there's a good chance you'll actually enjoy listening to these. I listened to a selection of stuff, from a live jazz performance by the evergreen Tony Bennet to the lovely acoustic sounds of Laura's Release Me, and despite my audio-snobbery and initial scepticism, I found myself enjoying the experience.
Before I go any further, however, I'd like to point out that you won't get as good a sound out of these as you will a pair of carefully-selected wired phones costing considerably less, but they are much, much better than most bundled earphones - good enough that you can tell the difference between a poorly-encoded 128Kbit/sec MP3 file and a higher quality 192Kbit/sec one.
In short, the Cerulean F1s are a mixed bag. For Bluetooth headphones they're relatively discreet, they're comfortable to wear, and sound quality isn't bad, despite a complete lack of bass.
Had the headset function worked as it should I'd consider giving them a decent score - it's the feature that gives headphones like these the edge over wired headphones, after all - but alas, it doesn't and that considerably reduces the F1s' usefulness. If you're after a decent pair of Bluetooth earphones/headphones for music and phone calls, I'd suggest you look elsewhere.