The 580EX II is Canon's top-of-the-line, professional grade external flash - There are very few features missing in this one.

but the 580EX II's significant power advantage can become important when using a flash modifier such as an umbrella, softbox or diffuser - or bouncing light off a high ceiling.I can understand making buttons safe from accidental changes, but these buttons are narrow and require an excessively deep press to make changes. The 580EX II is powerful, fast, flexible and quiet, and today sells used for next to nothing. If you're not using radio control and are using it on-camera or with optical remote wireless control, there isn't anything better. The 600EX series does recycle a little faster, but the power is the same (bolstered only by a slightly better reflector system at the longest zoom settings) and this 580EX II recycles super-fast. This 580EX II recycles in just 4.1 seconds from a full-power dump, and does it silently. It usually recycles instantly. Official weight is listed as 13.2 oz (375g) without batteries (4 AA alkaline batteries add 3.5 oz/100g).

The Canon Speedlite 430EX Flash features 6 custom flash function settings, the 580EX II features 14. I use my 580EX II when I need power, which is when I'm using it for daylight fill-flash at longer distances with longer lenses. Any of the smaller flashes are fine for every other use, and even for daylight fill if you're not too far away. The other primary difference is that the 580EX II can be used as a master to trigger remote Canon wireless slave flashes while the 430EX can only act as a slave flash. The built-in meter measures reflected light and turns off the flash when the proper amount is detected. The Senderwill control all receivers set to the same channel. Receivers set to a different channel will not be affected.Using my original 580EX flashes and a new 580EX II, I tested various scenario, camera, lens and setting combinations (including the While Canon originally recommended throw-away AA/R6 lithium cells, later Canon realized that they can vet very hot at high shooting loads and stopped suggesting them. More at User's Guide. As I am writing this, I need to personally decide if I will replace my three 580EX flashes with the new version.