I understand your frustration Macabre and suggest you start from the beginning and open a New thread. It really does have to be something your end and starting afresh from the beginning may help you resolve your issues.
Personally i rate Steam highly and i don't play much these days either so Cannot be accused of being a fan boy.
Whenever i do it is the Only prog to take advantage of my connection properly. Games run as smooth as silk my end and i have Never had a Single problem with Any of there games. My pings are below 10 and high for me playing source is a 20 ping
Updating the games is a breeze you just fire it up and let it work away no problems at all and no searching around for patches.
I really cannot fault them.