Carlos,
I agree with you 100% that these forum issues, are MAJOR issues that need to be resolved. I know that when the DotNetNuke.com forums don't work correctly people go to other locations as well as potentially other products because of the mentality that if they can't get it right who can.
I do know that the following items are known issues, based on discussions in other threads here on the forum (I'm not a member of the core or forum teams but I do spend a fair amount of time here on the forums...)
Post Notifications - These currently are ONLY working if you subscribe to a forum, however, you also receive notifications of your own posts. Thread specific notifications are currently not processed due to a bug in the notification queries not checking for a notification flag.
Post Notification Checkbox - If you check the box to "Notify me of new comments" on a specific thread, the setting doesn't appear to save, however, if you try to save it again you get an error about the violation of a data constraint
Moderation - Currently even if you are set to trusted you are being notified that the post must be approved, however, it is posting right away. Also it now appears that moderated users are posting directly to the forums as well
Now, there is one other issue that I am not sure what is causing it, but there are posts here recently that are breaking the entire display of a forum. i can't view the announce it forum right now because of it and a few others.....but I haven't heard any official commentary on this one.