When you share you story, please DON'T just say "I happy with GAE, bla bla bla ..." without any technology and business details.
I hope you can show as many of your app technology and business details as possible.
For example but not limited to the followings:
1. what language do you use (python/java/go, ect). ?
2. do you use the BigTable datastore heavily or lightly or never use it? (number of writes/reads Operations per day)
3. how many frontend and backend instances needed for you app? What are the types of these instances (F1/F2/F4/B1/B2/B4, etc.)?
4. how many active users per day of your client app, or pageviews per day of your website app? And bandwidth per day?
5. what is cost of your app every day? Do you care about the cost?
6. what is revenue of your app every day? Do you care about the revenue?
7. are you using other platforms along with GAE? What is the percentage of them from cost view (or any other views)?
8. is your GAE experience happy? Do you think GAE, comparing to other platforms such as Heroku, EC2 and VPS, will help you make more profit or not? (if you don't care about the profit, do you think GAE help you much comparing other platforms)
Hope the mods can make this thread sticky.