I've recently bought my 430 ex II. I'm not sure if it's the batteries dying or what but it takes a very long time for it to recharge its flash. It can take up to 30 seconds for it to recharge a cycle. I haven't had an opportunity to replace the batteries but the batteries don't seem to be that bad since they are still working fine and the LCD screen has not dimmed.
It's in ETTL mode as well. When the flash goes off too it isn't bright either.