Despite hours with a Tom Tom service rep, multiple new program downloads, switching wrists, bottom of wrist, gel, spit, cleaning of skin, etc. it never ever has consistent HR - not slightly inaccurate, a total fail, like reading 120 when it should be 165. Large function button is extremely easy to bump and mistakenly switch functions. Screen has 1 large display and tiny additional data lines - bring your reading glasses.
On the positive side, GPS is extremely accurate, battery life seems good, sync to iphone was quick and painless. As a GPS running watch it would be OK, as a HR watch it is an expensive failure.