It's good for me. Very close to chest strap results - off by 1-2 bpm most of the time if you run fairly stable. However if you do hills or intervals then there is a significant lag compared to chest strap - it only makes a difference if for example your goal is to run within a specific HR zone and need your HR to be precise right this moment (it is better to listen to your body anyway - you learn that after few weeks maybe months and then you only check/confirm with your watch once in a while). At the end of a workout your average or top HR will be the same anyway (maybe off by 1-2bpm), so if you only care about post-workout analysis then it's certainly good enough.
Same for me. Very good match with a HRM, under variety of conditions, and even with varying tightness of the wristband. However, it looks like it depends a lot on your physiology (especially on the thickness of the skin, and on the state of the veins), because you will definitely find here on the forum older posts of people who could not get it right and had permanent problems with the WHRM accuracy. Recently, I switched to Instinct 2, and I am very happy with the accuracy too.
I think mine is fine if I'm not doing much. If I jump up from sitting at my desk and walk around if often seems to go too high for a minute or two. It's not too bad for road biking; unreliable hiking and especially xc skiing... too excitable and worse than useless since it's inclined to get me alarmed about the overly high HR. It talks well to a polar H10 chest strap which follows my exertion level and heart rate exquisitely.
Do you find a significant difference in heart rate tracking with the IS2?
In general the results are in good coherence. Both between Instinct and Instinct 2, as well as between Instinct 2 and the HRM Pro. However, I still need to make more extensive testing side by side in all HR zones.
