I agree on the HR monitor
I agree on the HR monitor built in. This seems to be of more use to hypochondriacs than anyone else, but the using the term "water Resistant" vs "Water-proof" is found on the vast majority of products on the market, especially watches. You will find only a small minority of those are actually water-proof. This means the phone will withstand short periods of complete submersion in water down to 1m. In theory it means you are guaranteed you could strap it to your arm and go for a 30min swim without any issues, however the actual protection will probably last longer.