We used Parse, and (contrary to your suggestion) it helped us get to market
much slower and
much more expensively. We experienced a hilarious amount of downtime, and hundreds of engineering hours that could have been spent developing features for our users or improving our services were spent working around fatal bugs in Parse, which were usually not manifesting on all instances, which made it very difficult for the Parse team to diagnose them.
Fixes for Parse bugs were usually not forthcoming from the Parse team---and when things were fixed, more often than not the fix was reverted within a week because it caused something even worse.
For the first six months of our time using them, Parse would only report downtime post facto and backdated by a day. “F@#$k Parse” was perhaps the most frequently uttered phrase among all of us in our douchebag Mission district headquarters. What a life.
All the time, push notifications inexplicably stopped working for hours at a time---we were running a daily sales app, and this really killed us. It ruined dozens of auctions and pissed off tons of our users. But what's even worse? Parse made my life a living hell for a year, and I'm glad they're gone.