The sensor size seems to be a point of concern for many but as you noted in an earlier post there are some very good examples of shallow DOF from this camera.
What is of the greatest interest to me is the DR available from the sensor.
I am looking forward to that happy day when yours is truly here.
I am interested in your GoPro experience as you use it.
The DOF did look very shallow, especially at F/1.4. I think the fact that the lens retains it's minimum focusing distance allows you to really turn the background into mush. I didn't really get a chance to push it to the limit in terms of dynamic range, but from what I saw it's far better than DSLR's (as expected). 13 stops at that price range is just unheard of, I think you'll be pleased with it either way.
As for the GoPro Hero 3, it's amazing from what I can tell. Being able to control it from your phone is just awesome, you can change from 2.7Kcine/24fps to 720p/120fps in a few seconds instead of hitting those buttons over and over. The IQ is noticeably better, low-light is better, image is sharper, and the "Protune" feature is nice (gives you a more washed out image for color-grading and manual white balance control). I think it's absolutely worth the upgrade from the Hero 1 and even the Hero 2. I'd feel much better about intercutting footage from it with DSLR footage.
Also, the guys at the shop seemed super pumped about the Sony F5 (which looks amazing of course but is considerably more expensive). I can't wait to check that thing out, 4K, 2K Raw with high framerates, etc. I think Sony is going to kill it with those things.