I owned the VholdR and currently own the GoPro. I recently returned my VholdR because, after two exchanges, I was unable to get it to work properly. Perhaps these issues have been resolved.
The positives that I noticed for VholdR compared to the GoPro is:
It shoots a bit better in low light,
It's more compact,
It looks sleeker (the GoPro is pretty goofy looking on a vented helmet),
It has a rechargeable battery,
It's easier to direct the angle you're shooting at since it has the laser beams, and
It's marginally easier to use (when it's working).
On the negative side for the VholdR:
Quality control was horrible in my experience,
The battery is specific to the camera,
It's not water-proof, though it's water-resistant,
The stock mount is (in my opinion) simply horrible in design and functionality,
The other mounts are not yet available and cost extra,
It's more finicky,
It costs too much, and
The wind noise when you're going over 15mph is terrible and you can't shut off the microphone.
On the positive side for the GoPro:
It's cheap,
It's waterproof,
It comes with several mounts, all of which actually work,
Though it doesn't come with rechargeable batteries, it uses AAA batteries, which are easier and cheaper than the VholdR battery (and you can buy rechargeable batteries cheaper than the VholdR batteries),
You can play it on the TV really easily (though the quality is not great when it's blown up),
You can take pictures, including a picture every five seconds,
The interface is a bit more functional (i.e., you can erase videos, etc.),
It's more durable (e.g., you don't have to worry as much about breaking the lens or the cover for the lens),
You can buy a wide-angle lens for it (coming soon), and
It has 2 settings for noise, low and high, so you don't get nearly as much wind noise as the VholdR.
The GoPro does have less memory than the VholdR but you can easily remedy that by bringing along another SD card.
Given everything, I definitely think the GoPro is a better value than the VholdR, especially since there is very little difference in picture quality. I've also tested the VIO POV and that is much higher quality than either the VholdR or the GoPro, but also much more expensive. If they could figure out a way to make VIO POV have an image stabilization feature, it would be nearly perfect.
Of course, none of these works as well as an actual camcorder, but I don't have the time, money or energy to deal with that.