Does anyone have experience developing with Steam? How good are their community forums, documentation, etc.? Basically looking to see if they have good technical support. Anecdotes welcome...

I assume you ask about steam integration. There are no developer community forums for that. Documentation is quite good, but could be bigger and more detailed (it consists of brief high level description - details are described in the headers). Valve also provides a sample with full Steam integration, which is very useful. Integration is simple and painless, so I don't know anything about their technical support quality .