This is a product primarily cool because it has data to support its efficacy. No other way of using basal body temperature to guide natural family planning has shown efficacy anywhere close to the failure rates shown with this product.
Pros:

• Hard science to support its use.
• Looks simple to use
• Avoids contraceptive methods with serious possible side effects
  Cons:
• Subscription pricing can add up over time. $79. annually or about $10 USD monthly.
• It is theoretically possible to do the same thing without this app, but no one has shown other techniques to be equally effective.
• Has failure rates much higher than the "set-and-forget" methods recommended for those who want the most effective contraception.

Summary; It's great to have a proven natural planning tool available.