I've used Heroku off and on over the past couple years. I am not a fan, but it definitely has some good uses. Getting off the ground for free is nice. Uptime

I've used Heroku off and on over the past couple years. I am not a fan, but it definitely has some good uses. Getting off the ground for free is nice. Uptime was ok. I only remember one serious outage, but that was due to EC2. The support is absolutely terrible. On the free tier you get a somewhat canned response (not a solution, just a response) the next day. The more you pay, the more support is prioritized in response time, it's still not good. When asked what it took to get great support I was told that's an additional $2000/month and would give access to a technical account manager. That was most of a year ago, so may have changed. As far as page speeds and high traffic, that is very dependent on what you're doing. I was never satisfied with performance or latency building web apps on the platform. If your app is heavily client side, and server requests can be high latency it could work very well. I really can't recommend them for anything outside of proof of concept, or small non-critical sites. I currently use Heroku for this.