As long as you know where on your abdomen to place the probe (anywhere between pubic symphysis and the belly button) and be aware that it's only really possible to hear the heart beat after 15-16 weeks (as the baby has grown enough to now be out of the pelvis and heart beat is audible) and also be aware that the baby's heart beat is around 150 beats per minute and not around 70 (which is your own heart beat) then it's a great tool. Also, having the patience to slowly move the probe around to search for the tiny heart. As a doctor with knowledge of anatomy, I found this extremely easy to use and very reassuring before you can start feeling the baby move. It isn't as powerful as the ones we use in the hospital but it's definitely powerful enough to hear a strong fetal heartbeat. I discussed having a home doppler with my midwife and she says they do not recommend people get one as people typically do not know how to correctly use it. She told me some people place the probe near their own heart and claim they can hear the baby's heart beat.
So over all, use with caution! Excellent for the price paid, will continue to use it throughout pregnancy for reassurance. Would highly recommend in the right hands.