A year ago, Jawbone released a track everything wristband called the UP. The company, which had for nearly a decade made wireless headsets for cell-phones, gambled big with its smart wristband, dedicating millions of dollars and years into expensive R&D for an entirely new product. The UP could sense steps, sleep patterns, and a month’s worth of activity. It would then communicate with a user’s phone and help him or her monitor their health in a holistic way.

But the UP didn’t work. Or, at least, many models didn’t. The company pulled the band and offered a very public and widely applauded apology, which Fortune recently chronicled.

Call it the most expensive beta test in history. As of today, the UP is back — Jawbone announced its re-release this morning. The wristband was, in the interim, reengineered. As Hosain Rahman, Jawbone’s CEO, told Fortune, “The UP is now more life-proof. Liquid tests included blasting the device with jets of hot, soaping water, as well as Jack Daniels.” Stress tests had machines bending the bands in all sorts of terrible positions for days. Its battery charge is longer (10 days), its electronics more elegantly housed, its companion smartphone apps better thought-out.

MORE: Apple posts its gift guide for the 2012 holiday season

And yet, a year ago, the UP’s (first) release came after the product had been hinted at in TED talks and blogged about for months. The buzz this time around feels far less significant—in part because we’ve seen this product before, if not from Jawbone, from Nike (NKE) and FitBit. Will the UP, which costs $129, help bring about a revolution in personalized health? The better question, right now, is a lot more basic: Will the UP work?

I’ve just placed an UP around wrist (after giving it a few satisfying, Gumby-bends). A few colleagues have done the same. We report back on the device, and the idea of personal health trackers, after we’ve worn the UP for a few weeks. Stay tuned.