Baby monitors may have a visible signal as well as repeating the sound. This is often in the form of a set of lights to indicate the noise level, allowing the device to be used when it is inappropriate or impractical for the receiver to play the sound. Other monitors have a vibrating alert on the receiver making it particularly useful for people with hearing difficulties.
This unit only works until little ones can roll or crawl. It can be uncomfortable for some babies or ineffective if little ones are too small or their diapers don't fit well. We worry parents will rely on this kind of device to prevent SIDs and caution you that there is no evidence that it does or can prevent the incidence of SIDs. However, if you want to know when your little one is moving at a predictable rate, and knowing may help you sleep better, then the Snuza could be the right option for you that won't break the bank or require adjustments to your nursery.
Your phone might not have great battery life. Many parents who use a wifi baby monitor come to the realization that their smart phone battery life isn't so great when they are streaming a live video and audio feed from their baby monitor. If you have a newer iPhone or Android device, it will probably do pretty well, but if you have an older phone the batter is probably a bit weaker already and you will notice your battery life dropping pretty quickly during use. So definitely consider battery life and charging options for your smart phone when you are choosing between a self-contained versus wifi baby monitor.