I had my first O3 with my boss yesterday.
I have been doing O3's for the last 2 years and many other of the MT things and my boss noticed and has now started listening to the podcasts.
I prepared for my O3 by listening to the "O3's for the direct" podcast and did everything suggested. My boss told me that it really helped him and I felt structured and got through all the stuff I wanted to. It was brilliant. I have a good relationship with my boss and already feel it has improved!
The one thing I noticed I did wrong was (as Mike put it in the podcast) I "blabbed on". I didn't mean to but I was enjoying talking to my boss so much that I couldn't help it (I am in a virtual team so rarely hear from him unless there are issues or problems). We overran by about 10mins. He said it didnt'matter but I know he is busy and I am going to make sure they finish on time in future so it shows I am respectful of his time.
Thanks again MT for the brilliant advice you give!