This app does exactly what it says it will do. It is reliable, and I love the ability to look at the results over time using the graph function in history. The only drawbacks are (1) you have to put the iPad on a steady surface and (2) it doesnt work well in low light (which should be obvious since the app works via the iPads camera).
I use this app virtually everyday to monitor my training and overall health.
RomeBurms about Vital Signs Camera - Philips