I just tried race weekend. It's ok. Nothing spectacular, but not bad for a first effort. I'm sure it will improve over time.
You can set practice length, Q length, and lap count. As far as I could tell though, that's about it. You can also set the AI field pretty much however you want. Up to 23 AI on Mugello, didn't try anywhere else yet.
I run a quick 5 min Q followed by a 5 lap race. I enjoyed it.
I'll save everyone some confusion.... after each session has ended (practice, Q) a flag appears in the top left corner of your screen. To advance to the next session, click on this flag. I stared at my screen for a good 5 minutes wondering what the hell I was supposed to do after the Q session until I finally realized I needed to click that flag.