Yes I use it because it’s effortless and my needs don’t require expensive tiers.
Everything else I’ve seen will require more cognitive resources and learning specifics of the new setup - with no significant change in monetary cost.
I use Rails + Postgres + Redis + background jobs - a super simple stack.
I use deta.space these days. I have a much better fit with it because I often create small, experimental apps for my own pleasure and use. Heroku limits me and screams for payments. That blocks my creative process and makes me worry about unimportant stuff.
I still use Heroku for side projects. I used to use it for everything because we don't want deployment headaches on it at my last firm, but Salesforce was getting unpredictable with their other stuff so we moving everything over to Fly.io
Not thinking of leaving - it’s small niche app and don’t have much incentives to migrate.
Still using. Great service. Solid reliability/scaling. (Python/Django)
I am - Great for solo dev-ing.
i use koyeb.com for me
This may be an unpopular opinion, amidst a crowd who are maybe more comfortable with the whole deployment side of things:
I use super boring tech (React, Node) for fairly simple apps. When I was looking to deploy one recently, I looked at a bunch of alternatives, including the ones listed.
I couldn't get answers to even basic questions from the docs, and was in no way convinced I'd actually be able to deploy my apps. Plus the pricing differences were negligible.
Heroku was clever in that it worked to make deployment so easy every basic tutorial chose to use it. Its documentation is robust. I found it easy to use, and that counts for a lot with me, because that's not where I'm looking to spend attention. I want the damn thing up, and if someone can make life a bit easier, yay.
I'm only writing this because I think the vast majority of these companies' clients are probably closer to the profile of someone like me. Meaning, they're a little apprehensive about dealing with deployment trouble, and trying to minimize that specific risk.