I'm not sure what to think about Head-on head angles.
I've been struggling with that question as I'm reviewing my own files.
I'd like to hear from others on this forum but my best guess is that Head-on rarely works.
However, in this case it does give you a good look at the gorget.
Plus, as best as I can tell the eyes look like they are in focus.
Despite that I don't think it works.
Another issue is the use of flash. I see it like spicing. Some like it hot and others don't.
Personally I think flash is most effective if no one can tell that you used it. In this picture it looks to me like flash was used.
You might try a -2 stop setting or lower.
Head-on is definitely working for me in this image. Both eyes showing (with catchlights), gorget nicely displayed and the chin (beak) up pose gives it a lot of character.
And honestly, I'd take a head-on look any day over a head turned away look (which you seemed to prefer in your last two posts)
Does have a flashed look, but I think you can tame it in post processing.
The perch is minimal and excellent. I'd crop from the left a bit.
I photo hummingbirds a lot and even though I'll shoot some head on, it's usually only when they display really vibrant colors like Anna's hummers. Here is an example: http://www.az-pics.com/Arizona/Wild-Life/i-WB4LxKM/A
I also have to comment on the "flash look". A bit too much, stopping it down another full stop would help or use a multi flash set up. It helps reduce any kind of shadows, allows me to shoot at a higher smaller aperture for better detail.
Keep them coming, I like looking at all kinds of hummingbirds.