We have identified several bug fix/enhancement requests to Google.
1. Calendar Loading issues: from time to time a resource or personal calendar fails to load. We have created tickets for a number of these occurrences, as they are reported to the Help Desk.
2. The ability to save a meeting which requires an already booked resource has been reported to Google as our number one issue. At the least, we expect to see a warning come up prior to saving the meeting.
3. When a meeting is scheduled that involves a number of different attendees and a conference room at a time that is available to all, we find that subsequent views of this same meeting show confusing results. Some attendees will have nothing in the time slot (in the "Find a Time" tab) and others will have a single bar labeled "busy"). What you see depends on the permissions you have on the person or resource calendar. See this FAQ for more info.