I've been wearing my Jawbone Up3 for about 6 months now and wanted to post an update. I went back and re-read my initial thoughts and much of my feeling remains the same.
I wear the tracker all the time, except when charging and showering. It does seem to be somewhat water resistant as the recent super hot weather have resulted in some pretty sweat-intensive workouts. I remember having some irritation from the band the first few weeks, particularly at the metal contact points. When that happened, I would switch to wearing the band on the other wrist until the irritation cleared up. This only lasted a short while and I've had no problems since. This tracker is so small and lightweight it is really easy to wear all the time.
The step and workout tracking works very well for me. The app provides good statistics and feedback on how I'm doing. Every Monday I get an email summary of the past week's activity and sleep records. I also discovered that by going to the Jawbone website I can download my statistics to a CSV file to see even more data. Year to date I've taken 1,644,937 steps (yay me!!) but I can see I am inactive far more than I am active (ugh). I love the inactivity reminder, especially on work days when I find I'm focused on projects for long periods of time and easily lose track of how long I've been sitting. It's a good reminder to get up and move a little. Now that we are walking most every day, I hit my 10,000 step goal at least a few times a week.
While I guess it's not super useful, I still dig the sleep tracker. It's interesting to see the statistical quality of my sleep compared to what my impression of the quality of my sleep is.
I've been most disappointed in the heart rate tracking. Jawbone has been saying since well before I bought my tracker that on demand heart rate tracking would be added in a future firmware update, but this still hasn't happened. The band is supposed to monitor your resting heart rate periodically throughout the day when you are still. Some days it takes many readings other days it takes very few, regardless of my activity. I find this annoying as it makes the statistics less accurate.
Battery life is also a bit disappointing. I get about 4 days on a charge before having to recharge which takes at least an hour. The app is also pretty draining on my phone's battery so I tend to only sync my band two or three times a day.
The final disappointment is the physical condition of the band after 6 months of use. The tracker unit is metal coated in black paint. The paint is wearing thin across the face making it look shabby. And then the band broke this week. The silicone split about half an inch from the head of the tracker. My guess is because my wrist is a little small there's probably a stress point there which resulted in the break. The band is not replaceable, the tracker is integrated into the silicone band and Jawbone won't replace it because I purchased on open box item. Fortunately I was able to glue it back together with super glue and it seems to be holding fine.
I will continue to use my Jawbone as long as it holds up, but I wouldn't buy another one. At least not of this model. I'm looking into a tracker with a replaceable band that would also have a display so I don't have to sync up to my phone to see updates. I've found one that looks promising and I'll be sure to post if I make the switch.