1) Price Guide: During the GoPro Hero offers 4 Black Edition for 499 dollars in America, which for a few months (summer '14) corresponded to less than 370, it was offered here for 449. After GoPro, due to the weak euro, the profit margin was apparently too small, the retail price rose to 529! Mind you for the exact same product. This product practice towards the EU and their citizens, I feel almost as impudence. The value for money I can therefore at best rate with poor, even compared to the competition (-> Sony)
2) "GESCHUMMELTE" slow motion:. For me, especially the slow motion (120 frames per second at 'normal' playing with 25 or 30 frames p.Sek thus 4-5 times slow motion) was interesting. This should in FullHD (1920x1080 pixels) and thus be with Hero 4 Black first time in a resolution feasible that I enjoy also the traditional PC monitor. Unfortunately, I feel the quality as extremely poor. It does not correspond to what I FullHD or good video quality even imagine only rudimentary. "Photo Mike" could also do this with figures prove in its previous review: Instead of the expected ~ 140 MB video was his only 46MB in size (factor 3 !!). This is also my subjective impression. I suspect, therefore, that the GoPro internally only the 'small HD' (HDready: 1280x720 pixels) and takes just upscaled the number of pixels. The video has then indeed the FullHD resolution but only the quality of HDready.
Either GoPro manages just not the slow motion function in FullHD properly to implement (please do not advertise!), Or perhaps it is also intended to ensure the quality of a successor improve again aware (sad Product Policy).
3) SEVERAL SMALL THINGS: The apparently profit maximization more and more determined at GoPro that objective, appears to me at several little things: The price-performance ratio of the accessories is much the same annoying as the camera itself (eg "Floaty Backdoor "an air-filled plastic cubes for 21). I find the build quality of the 4 compared to previous versions in addition not as an improvement but rather than deterioration. There are also a number of smaller 'design flaw' that are at best annoying (errored firmware / updates,) but in the worst case can also destroy a recording (WiFi noise in soundtrack).
4) CONCLUSION: GoPro claims the Hero4 Black THE ACTION CAMERA simply built to have. For an undisputed top dog, of which I expect absolutely good performance at a fair price, this GoPro but must leave far too many feathers. The competition is not sleeping: Sony offers the Sony FDR X1000 also a 4k Action Cam, which is slightly better of the performance according to various test but just over 400 costs.