It's genius to get started quickly, but quickly becomes an architectural nightmare. If you need to change a query and the logic is in the mobile app then its going to be days before Apple approves a new build, and even longer before the user updates to the latest version. If your logic is on the server side then you roll out the new code and you're done.
Pushing the need to be up 24/7/365 onto an external service with the manpower/funding to succeed at it reasonably well is generally worth it.
Devops here. The only service I have ever found to have anywhere close to 5 9's of reliability? S3. That's about it though.
EDIT Since I'm rate limited:
> I don't think any product exists that's going to remove the need for ops experience. I haven't used Parse, so I can't comment on its reliability.
If you are an app developer whose backend consists entirely of talking to an API, I'm uncertain exactly what "ops experience" on the server side you believe is needed?
I don't think that's ever going to be possible unless both people forgo sleep and are willing to drop whatever it is they're doing to attend incidents.
I'm really surprised by the number of responses of the form "but I could run that cheaply myself on my own server!" I see to online services.
Admittedly, if you know what you are doing, you can build a reliable, distributed backend but that isn't a skillset most App developers have.
I've had ~4 on call events in 5 years and all of those I could wait at least 9 hours to resolve. Certain situations allow you to do that sort of thing.