My Mom has one and it is awesome. But I really can't compare it much because before her Jawbone she had some free one that came with the phone that was garbage.
I have a Jawbone (original version). Nothing comes even close to the sound clarity and noise-canceling software it uses, because its based on military technology.
The unit l have looks pretty bulky compared to the new model (as well as most other bluetooth headphones) but it's downright indestructable.
The only downside is the OEM ruber earpieces SUCK! So I bought some aftermarket clear Jabra earpieces and superglued one on. Now my jawbone fits perfectly and snugly and I don't have to use the ghey-looking metal and rubber ear loop either.
I'll probably buy another when my current one dies. They're averaging about $40 to $50 online.
My friend with a Treo 755p loves hers. Had the usual problems with every other earpiece she's tried. I found one for $99 online that I'm thinking of springing for if I can't find a stereo bluetooth that I like AND works.