Have this Pixel Mago Speedlite for about a month and a half now. Here is the comparison of Mago with Canon 550EX and Yongnuo 565EX.
The SIZE is the matter
As show on the above photos. Pixel is the LARGEST in size and also the heaviest in weight among these 3 flashes. But Mago is the only speedlite that has LED model light. This model light can be handy when you need a small light source, It also has a usb port for firmware upgrade and a PC sync port.
On the report from my first impression. I mentioned about the battery drain. In fact, the battery indication logic must be buggy. After you left the battery in the compartment for some days. when you turn on the unit. Battery indicator will show empty after a while usage. I was pretty sure I have put in new batteries the last time and I did not shoot much. I took batteries out and put them back in. Battery indicator show FULL POWER again. So Pixel has to take care of this. I hope they can correct it on next firmware update.
When I used it on my camera camera (Canon 5D III) hot shoe. TTL work fine. Manual adjustment work perfect too. HSS work as expected.
For my work that is mainly wedding. My setup is using Yongnuo YN-622TX and YN-622C TTL remote trigger to control all my flashes. From my testing. I have over exposed photo every once in a while. Manual setting using YN-622TX is not working as well. I have hard time to control the flash intensity. Good news is I just update YN-622TX firmware from 1.02 to 1.04. I have not test the setting in real wedding shoot yet. Manual setting seems kind of work now. You have to release the flash before new setting take effect. It is like working with an old school strobe. Yongnuo 565EX do not need this at all. That is not a big problem but I think it can be fixed soon. As for TTL, I don't have miss fire or over expose in a series of shooting for about 30 frames.
My typical Flash + Trigger + Camera setup
Samples from my work using Pixel Mago
So far I'm pretty happy with Mago and I expect Pixel can have firmware update soon. Battery drain/indicator problem is a real deal to me. I use up batteries so fast because I can't tell it is the fault from the indicator or batteries really gone.