Uptime they are good no noticeable problems and the network speeds are excellent. They are actually built upon amazon cloud.
The downside is the cost. Yes, they get your app up and running with little to no maintenance but you do pay for the privilege.
Personally I use heroku as a development and deployment platform before moving it to a cheaper solution once I have the time.
> Does Heroku offer any value for people who know how to set up servers but are inexperienced with larger setups / load-balancing?
Yes! time is money, so even if you know how to setup a server having it all automated is a massive time saver.
That being said as you scale so will the cost. At some point you will want to move provider and then you will be in the situation of still having to setup and run your platform.