I bought this bag as an on the go bag for my Nikon D5000--since simply hanging the camera around my neck all day made me WAY too nervous! The bag fits the camera and the 18-55 lens perfectly, and has room for me to carry an extra battery. I like that it has a hard bottom, so then you can sit the bag down without having to worry about the camera tipping (something you don't want happening with a DSLR!). It can be a bit awkward to get the strap in the bag as well, but I've found tucking the strap around the lens works well.
If you're looking for a bag to carry your camera and all of your lenses and and gear, than this is not it. But if you want something to carry your camera and your primary lens while on a trip or out and about, I think this is a great option.