I have a Garmin 235 and the heart rate monitoring also sucks. I think now it just stopped working but when I got it new it was sort of maybe accurate indoors when you're not moving. As soon as you go running or outdoors where sunlight can interact with the sensor it's basically useless, either measuring your cadence instead of your heart-rate or just producing total garbage. So I bought a polar chest strap which is incredibly reliable.

It's been a while since I looked at reviews but when I did the conclusion seemed to be all wrist based monitors are iffy and vary greatly from person to person. Maybe some people have a stronger signal at their wrist?

EDIT: I do like the watch though. Lightweight. Durable. Long battery life. Accurate GPS. Everything I need to track my running.