The camera I loved when I used once was the Sealife. It is a bigger, regular size camera, but the buttons were designed for divers, the display is ultra-sharp allowing you to frame what you shoot, and the quality superb. Pricing around $450 the cost of GoPro with all the extras. I also think that Sealife autocorrects colors very well... I would take a look if I was looking for a camera. GoPro is compact but you pay in quality. Check out the Sealife DP 1400. I think that is a nice diving camera...and can be upgraded with strobes to add photography quality.
I have both the SeaLife DP 1400 and the GoPro Hero 2 with a Backscatter red flip filter. First, the only time I have a shut off problem with the GoPro is if the battery is used up. Some batteries are better than others. I'm using several 16 GB class 10 standard size SD cards. I can easily get 3 dives off of one card.
As for the SeaLife. It's a good inexpensive camera but it has different uses than the GoPro. I use it for still photography. It does a prettly close up macro, but often takes forever to focus and it won't take the picture until it thinks it is focused. As a result I run it in burst mode and take several shots to hopefully get one. The closer the macro the longer the focus before taking the shot. The SeaLife will also shoot decent video, but it is not wide angle. The wide angle makes a big difference on the video.
Right now I have both mounted to a single tray and pay attention to the SeaLife and just let the GoPro run the whole dive. Seems to work quite well.
An edited example from the SeaLife, the shell is about an 1-1/2 inches across.