UPDATE: After circa one year the watch strap has broken. Not impressed as it has been well looked after, however full marks to Amazon for an efficient no quibble replacement. Reduced the score to 3 stars from 4 stars.
Good, but room for improvement. The good bits: - it's fairly small and discreet. - most functions work well - battery life is good, I only charge mine twice a week. - step counting pretty accurate. - Setup (syncing via android phone) was easy and works perfectly, also seen multiple S/W upgrades go through so being actively updated. The flaws: - the textured finish means it catches on shirts, and worse bed sheets. It's just not usable to track sleep. - the strap is really quite short and seems flimsy. - sometimes it seriously under measures heart rate, struggling to adjust to rapid changes. Seen it both on a real bike and static trainer, when it says my heartrate is very low, even though I'm cycling hard. Usually after a while (15~20 minutes) it suddenly starts measuring correctly. See image - all the period shown I was cycling hard and heart rate would have been around 140~150. After that it measured correctly for the rest of the 3 hour ride.