I got a GoPro 3 Silver (or whatever the second most-expensive is) and I have had many difficulties with it.
I purchased two 16 GB micro SD cards, at first neither one was capable of recording a video without ending by itself, or freezing completely resulting in me having to take out the battery.
Then I decided to install the update, one of those two SD cards is still not working at all, but the one that I used to update the GoPro has worked sometimes. Yesterday, it successfully recorded about two videos around 30 sec each. It failed on about 15 or so. That's a pretty poor ratio and extremely frustrating when you're really trying to get a shot and are in the zone. In addition to the camera freezing or stopping the recording on its own, when I got home to view the footage, some of the MP4 files were not able to open.
Today was a different story. I updated the GoPro again this morning (same update), and it worked perfectly for me today out skiing. All MP4s were capable of being opened. Today was the ONLY day so far (15 videos, probably 5-6 minutes of footage) in which my GoPro didn't suffer some problem.
Because of these problems, I have a suspicion that my memory cards are to blame. I will probably invest in getting a better micro SD card. Also, I am pretty sure that very few people are experiencing the problems that I am experiencing, but an employee at a GoPro tent did say that a person came in with the exact same problems I have.