Saw this last night. It completely flew under my radar and wouldn't have even noticed it had it not been for a friend of mine pulling me along.
I'll say this is a very good "proof of concept" film, and will most likely go down as a cult classic. What I mean by "proof of concept" is that this is one of the first first person films made (I think there is an old black and white Hollywood film from the 50s that might be the very first). It proves that it is possible but there are still some obstacles to overcome. Most importantly is to invent some kind of Steady Cam for GoPro, and while they do their best to reduce shaking, sometimes it is inevitable.
The fighting scenes and parcour are awesome. Suffering from vertigo myself there are some climbing scenes that have me at the edge of my seat. But to be honest, the thing that really ties this film together, and makes it worth watching is the role of "Jimmy". Seriously, this actor has one of the best parts I've seen in a long time, and pulls it off fantastically.
I would recommend it, to be honest. It's very "fresh". Sure, the story won't win any awards, and I've already mentioned the limitations that GoPro has, but all in all, I think people who enjoy new things in cinema and/or FPS games will enjoy this.
I hope they get enough money from this to continue developing this type of film, as I think it has a good future once they solve the issue of stability.