Well apparently
negative criticism is considered as "trolling" or something around here. Thing is, I
really want to get my opinion across, so here is version 2.0 of Feedback
Nega!
This is the buzzer sprite from the Wai prototype. It was depicted as looking down, evidently keeping tabs on Sonic. It ended up being tweaked for the final build:

The buzzer is now not looking down, but was intentionally changed to have a blank, almost innocent gaze. This was a conscious design decision, and not just lack of detail attributed to the small sprite size. However, this is what was actually depicted when the enemy was drawn in large detail:

This is not a new thing. Most of the time there is a large disparity between official artwork and in-game sprite. But right now I'd just like you to notice the eyes once more. Again, they face downwards, much like in the prototype sprite, however, this time, a further change was introduced -- the buzzer is clearly irritated! So which is it? Dumbfounded look, staring at the horizon, or angry, eyes fixated on the blue hedgehog?

This is what you presented as an upscaled sprite. It is clearly based more on the official artwork than it is on the original sprite, which is in no way a bad thing. However to be honest it took me a while (and I had to squint close at the screen) to figure out what was going on with the eyes. Frankly, they look messy, and it's hard to read them without paying close attention, something which would undoubtedly be even harder when you're playing the game and everything is in motion. So I think you should clean up the eyes, like so:

What I've done here is straighten out the eyelid, giving a clear, menacing look to its eyes, and more importantly I've removed the shine on the eyeball which was not there in the official artwork, and was frankly adding too much visual noise to the picture, inhibiting perception of what was actually going on.

Alternatively you could reinstate the child-like look to its face, which is still cute and obviously fits with the consistent design of (most) enemies having big, cartoony eyes despite being lethal threats to the player.
Also, the animation job is great, but the jets are needlessly long.