Using bleach you need to rinse it all off of whatever you treated/sanitized with it to remove the chlorine. Otherwise, it will F-up your brew (gives a nasty flavor that won't go away)...
StarSan is a no-rinse sanitizer, so you just mix it up to the correct concentration (easy to do since the container includes a way to measure for the amount you'll be mixing). Basically 1oz in 5 gallons of water. You simply dunk what you're sanitizing in it, or swirl it inside the item (for fermenters) and let it stay in contact for a minute, or two, and then drain/remove...
The foam created by StarSan is also no issue for the yeast (it's been mentioned that the yeast will actually eat it).
I would highly recommend using a no-rinse sanitizer (there are a couple of options) over bleach every time. I've been using it since my second batch and it's been working great. I even have about 3.75 gallons of it mixed up right now. I typically make 2.5-3.75 gallons at a time, keeping it in a covered container. This way, whenever I need to use some, it's already mixed up. It also makes it much easier on bottling day, since you have less work ahead of you to sanitize.
Another benefit to StarSan, IMO, is that you don't need to worry about color indicators for it's effectiveness. This is important for me, since I'm color blind. Plus, with StarSan, there are no harmful fumes produced by it. Unlike bleach...