i've used the Canon 550, the nikon SB28, metz, and sunpack.
now, I'm having the 580EX II on my 1D mark ii. it is very nice evolution of their flashes.
these are the things i like:
o the simple layout of buttons and dial,
o the battery door is better than the old stuff,
o water resistance hot shoe and many places,
o 1 sec modeling light for upto 10 times (then rest 10 min),
o slightly faster recharge,
i don't like these:
1) this is 2007. the flash still use C.Fn "some number" to represent the words such as, "auto power on", FBE, and etc. I know with 1D markIII, some of the menu can be driven from the camera. But, I don't want to upgrade my camera just because of deficiency of the flash. Any user should be able to read from the flash to tell what they are changing instead of carrying the menu.
2) since water resistance is one of the selling point, why aren't the four buttons across the back use a plastic covered button? It is liked I don't wear a rain jacket (no water resistance on buttons), but, I do wear a rain pants (water resistance on the hot shoe and other area). So, I will soak from top, might not happen with the bottom.
3) when I use an external battery source, liked quantum, can i skip the 4 fresh AA, please?
4) when I use an external battery, can the circuit on the flash smart enough to sense the external battery and change the CF stuff by itself? It is 2007, Canon.
Now back to enjoying photography. :)