That's all? Worked FINE!
I'm saving on the 580EX and until I shall have the money scraped together, I have ... nothing. (On-Camera flash, sure, but...)
Using flash while shooting outdoors is great, IMO. It takes a bit of power to shoot subjects who are farther away...but the 430 and 580 especially are pretty good.
The trick is being able to keep the shutter speed under the camera's max sync speed (1/250 in my case). It's a trade off though...because if you stop down the aperture to get the shutter speed lower...the flash has to work harder because of the smaller aperture.
Both the 430 & 580 had 'High Speed Sync'...which allows you to shoot at shutter speeds higher than the max sync speed....but this greatly reduces your range and uses up the power fast.