After launching Collect we saw:
1) 10.53% relative % difference in NAUs
2) 12.76% relative % difference in average bookings per user (for existing users)
3) 40% relative % difference in 2-year LTV (early indicator for new users)
One lesson learned was that notifications are not easy. Addressing concerns on privacy, annoyance, and language are key to success. However in this process, we also took the opportunity to further our notification engine work and best practices to sending notifications as well.