Experiment in your own dev or demo app with a web and a worker dyno for free. Sleeps after 1 hr of inactivity. Active up to 12 hours a day. No custom domains. 512 MB RAM.
Run a small app 24x7 with the Heroku developer experience for $7/dyno/mo. Custom domains. Run a maximum of one dyno per Procfile entry. 512 MB RAM.
Build production apps of any size or complexity. Run multiple dynos per Procfile entry to scale out. App metrics, faster builds and preboot. All Hobby features. 512MB or 1GB RAM. $25 or $50/dyno/mo.
Isolated dynos for your large-scale, high-performance apps. All Standard features. Compose your app with performance and standard dynos. 6GB RAM. $500/dyno/mo.
All dynos come with the core features of the Heroku platform: Git-based deployment, managed patches and updates, automatic dyno restarts and aggregated logs.
IMHO
The free option is much less attractive now- projects that don't make money will have to move to other services. This means you will be driving many developers (myself included) towards your competitors.