It’s surprising how good phones are these days, both for cameras and, indeed, for mic’s.
It’s also surprising how good some pretty cheap mic’s can be …. sometimes with a bit of software help, which I guess is cheating. .I have a dead cheap Behringer mic that cost me about a tenner, and with minimal processing in a audio app, provides a passable impression of a classic and standard Shure SM58, which is about 10x the price, and has been something of an industry classic for decades. The downside is that it’s a standard XLR connection so to get audio into a PC you need an audio interface and they can be, well, there you do tend to get what you pay for and mine was relatively inexpensive, but still about £180. Then again, the same is true of that Shure, you still need a pre-amp/USB i/face to get audio into a PC.
You can get pretty decent mic’s that are inherently USB, and don’t need the separate interface, but good ones still aren’t especially cheap. Say, £100-ish. All things said and done, it is certainly possible to get far better sound BUT, unless you’re earning from it, is it worth forking out £100 (or somewhat less, or a LOT more) on a microphone to do a review you’re not getting paid for?
My perspective on that is that the audio isn’t that great, but the information in the reviews is, and the audio is certainly good enough to hear what you’re saying …. most of the time. There are the odd moments when when I suspect you’ve moved just a bit too far away, or a bit too far off axis and the sound drops right off for a few moments, but is the audio still perfectly serviceable? Yep.
I’m pretty fussy about audio quality, and there are more than a few vid’s (not including yours), especially on Youtube, where the audio is so bad they’re not worth listening to. With me, they last about 10 seconds. Yours, I’ve watched the reviews on things I’m interested in right the way through, and several of them, several times. Like the Niche ones.
If you were doing that for a living, my advice would be upgrade the sound. In many cases, sound is more important than the video. But you’re not, and the sound is certainly good enough.