When I started writing my first-ever iOS app (coming from web dev) the only thing I knew about App Store subscriptions was that they were annoying and hard to get right. Being a noob to iOS, Swift, and the App Store I was not looking forward to figuring it out myself.
Fortunately these guys were launching at the same time we were and offered to let us into the beta. Dropping in the SDK saved me literally months of stumbling around in the dark trying to do it myself, poorly.
Support has been top notch and they're building out new features constantly.
I tried out RevenueCat because I never really understood the iOS subscriptions API and just cobbled together a barely-working implementation. RevenueCat gave me the peace of mind that comes with a professional, expert implementation.
Also, there are surprisingly few products out there that provide analytics on subscriptions. When gauging ad campaign effectiveness, I needed to be able to see accurate metrics on my subscribers. What's their churn? Which cohorts are staying subscribed the longest? How many subscribers do I retain after x months? RevenueCat is unmatched in this regard (believe me, I've tried them all).
Lastly, something that I love about RevenueCat is the ability to see an individual customer's transaction history. I can see when they renewed, when the started, and further, every transaction they've made in my app since the beginning.
I'm super excited by what the RevenueCat team has cooked up this far and am super excited to see what they introduce in the future! Jacob is the man!
The iOS SDK was trivial to integrate, and the nice folks at RevenueCat have been quick to answer any questions in the most helpful manner. Their product is solid and I can't recommend it highly enough. If you're even considering implementing the StoreKit APIs yourself instead, do yourself a huge favor and checkout RevenueCat before you go any further.