Just got my hands on the SJCAM C300 and wow, this little guy packs a punch for its price! Here's my honest take after using it for a week.
The Good: That battery life is no joke - I recorded my entire hiking trip (4+ hours) without swapping batteries. The dual-battery design is genius, especially when using the stick battery as a grip for vlogging. Image quality at 2K is surprisingly crisp, and the waterproof case survived an accidental pool dunk during testing.
The Okay: The touchscreen is responsive but too sensitive - I've accidentally formatted my SD card twice already. The stabilization works decently when mounted (helmet footage looks smooth) but handheld shots still show some jitters. And yeah, that "4K" label feels a bit generous - it's more like upscaled 2K.
The Annoying: Had major WiFi connection issues until I realized you need to press the mode button while connecting (not in the manual!). Audio quality is serviceable but definitely needs an external mic for serious vlogging. Also wish they included a basic mic windscreen in the bundle.
Final verdict? For under $150 with all those accessories included, this is probably the best value action cam right now. Just don't expect GoPro-level polish - think of it as that scrappy underdog that punches above its weight class!