Compared to what? An Arri? Bebause on its own, as far as smartphone video goes, it's quite fine. You can also trivially shoot a higher bitrate (not ProRes) in Filmic Pro and other apps.
The main problem that I see is compression artefacts, especially in complex scenes with a lot of motion. For example filming a person or pet moving against a background of grass or gravel, or the camera panning across complex terrain. I even got it really badly just filming waves going in and out on the beach.
I know these are tough situations for to handle but it feels like bumping the bitrate would help a lot.
Dude this isn’t 2011. The “average YouTuber” these days is shooting on full frame Sonys, Blackmagic, or even RED.
YouTube is not a shoestring operation anymore, filmed with whatever point and shoot digital camera is at hand, and for most even semi-popular creators it hasn't been like that for some time now.
I thought it would be constructive to point out that most pro or semi-pro YouTubers are now using top of line kit, with full post-production pipelines tailored to YouTube.
If you know this already and yet still expect your iPhone to match up, then ok, perhaps you're right and there isn't a constructive conversation here.
If you don't have video experience, then you might find it subpar when actually you compare it to impossible standards and 10x more expensive gear and lenses.
And even ignoring the limitations of the sensor, the iPhone isn't even the best smartphone. Due to the fact that it can only record variable framerate video it's basically unusable for professional work, even with the Pro model in ProRes.
Interesting, I've always thought the iphone camera produces extremely good results. Subject to the obvious limitations like not being able to replace the lens! What sort of benchmarks should I be looking at, to really measure the camera's limitations?
The quality difference is massive, and not in favour of the iPhone. Apple has awesome algorithms to post-process these images, but garbage in, garbage out, you can only fix so much.
A larger sensor means you naturally get much better low light capabilities, much better bokeh, and the ability to increase the dynamic range without losing resolution.
What e.g. Google Pixels call "HDR+" is what high end Canon cameras can do at 24 frames a second, due to the higher dynamic range of their sensors and the integration of two independent gain circuits.