I currently own the Basis watch,
http://www.mybasis.com
This watch comes with HR monitor, skin temp & perspiration, as well as the basic pedometer/moving calculations.
They recently updated the firmware & software to track more sleep detail - including deep, REM, etc.
Sample sleep data attached.
My experience so far
Pain to sync - Ive owned fitbit devices before and they are not finicky like basis - though they track less data too.
Battery performance is low.
Ugly watch.
Dim, very dim display.
Software - and here is where Apple could do some disrupting - ok, lots of data, but what does it all mean? They comment on their forum, in response to questions, if the sleep score is high, indicating *good* sleep, so why do I feel like crap? Their answer is basically there are lots of *factors* at play, which affects how the person feels. LOL. We all know that intrinsically, so if the data doesn't correspond, or reveal those parameters that might play a role in the final result, what's the friggin point????
What do the measurements really tell us, & what areas do we change to improve, etc?
There really is nothing along these lines in terms of the software analysis (for any system). IMO, a typical new user will become disinterested in the novelly aspect if their isn't any real value. One or two generations, and sales might suffer if this is one of the principal selling features.
I thought that with the additional info, the calorie tracking would be more accurate, but Im not sure this data is incorporated into the calculations - some forum threads indicate it is not. That would agree with my experience, as the fitbit is within 1% (or less) of the Basis results - indicating they are using traditional formulas, age, weight, steps....
Im very interested in the bio-data, obviously. But without some sensible software that is actually helpful, not sure how important this will be in the long run.
The other features such as facilitating less need to have a phone in hand, e.g., weather, texts, etc, would be as important - if not more - in the event Apple can't come through with intelligent collection & analysis of the bio-data.
One exception - for diabetics, clearly having glucose monitoring is a big, big result. It would take a company the size of Apple to get the proper certifications, etc.