Serial Reader is great! I came across it a year ago while looking for a service that would let me read classics as email newsletters.
I used it for a couple of weeks. The app is slick and it has some really cool features (like letting you import your own ebooks) but I kept forgetting to open the app and then falling behind. Also the daily reading length of 20 minutes per day felt too long for me, personally.
Ultimately I got it in my head that I'd be more likely to actually read issues if they showed up somewhere that I already had a habit of checking daily (my email inbox), and if the issues were shorter (~10 minutes each) with more fine-grained controls about when they were delivered. So that's what I built!
I actually emailed Michael (the person behind Serial Reader) back in June, hoping to get his blessing to use the word "Serial" in my product's name. Never heard back and eventually I decided to move forward with the name.