I'm no expert on these things, but after listening to various tests online -- it sounds pretty decent. Virtually no noise and it sounds warmer than the VideoMic. For me, anyway. If a sound expert could chime in, that'd be cool.
What speakers are you using for your audio listening and in what kind of environment? I listen on about $2.5k worth of speakers in a sonically isolated, acoustically treated room. I hear every little flaw - every bit of hiss, every rumble, every mumble and growling stomach, every piece of grit on the floor. My work is ultimately supposed to be screened at festivals, meaning it will be heard on a quality theatre speaker system. And that's where the substandard gear and lack of technique smacks you in the forehead.
If you're making videos for practice and for fun anything goes; if you are serious about your projects and career you need to pay serious attention to gear and technique. Hiring a professional is always my first recommendation, finding a hungry knowledgeable up-and-comer is next, DIY is last on my list.
There are a multitude of factors that influence the quality of the sound. Self noise is inherent in all audio products, cheap/inexpensive products tend to have a lot of self noise.
Inexpensive/cheap products also tend to color the sound. Sound coloration is actually useful for music recording, but is not welcomed when doing production sound.
Signal path is how the audio moves through the various audio devices - the mic, the preamp, the mixer and the recorder. They all will impart noise and coloration. How much will depend upon the quality of the gear and proper set-up.
Gain staging is obtaining the best Signal to Noise (S/N) ration - how hard you can push the preamps and inputs in the signal path before clipping/distortion occurs.
Higher bit/sample rates allow for more headroom and less aliasing during processing.
None of this addresses
how to set up a proper signal path,
how to do gain staging and, even more important,
how to do proper boom and lav technique.
And all of this is stuff you need to know in order to capture solid production sound; audio post brings in a whole other set of creative, technical and equipment needs.
Audio is a very involved topic, which is why I recommend pairing up with someone who knows more than you do. There are no "magic bullets" that will give you great sound; only knowledge and experience can do that.
After all of this off-putting drivel my point is that there comes a point of contradictory diminishing returns. You can have great gear but without knowledge and technique you'll still end up with crappy sound. But all the knowledge and technique in the world will do you no good without at least the basic equipment needed to do the job properly, the first of which is to continuously listen to what is occurring on the set through a pair of good closed-back headphones. As I mentioned in a previous post if you are using a DSLR you have to think the way you would if you were shooting on film. Real film has no sound recording capabilities at all; you must have a separate audio recorder. If you want the film look you have to pay the price.
