Lowepro's website quotes the internal size as 16.0 X 11.0 X 26.0 cm but I measured the depth as 27cm, so you have a little more room to play with. The documentation that comes with the case states that it should be OK for use with a DSLR with attached lens (up to 80-400mm f4.5 or 100-400 f4.5. That looks about right.
The padding feels quite substantial so should offer reasonable protection against minor bumps, and the case looks and feels well-made. A broad shoulder strap is included. A spacious front pocket holds batteries, filters and lens caps, and will even hold my 18-55mm lens. A rain cover is concealed in a pocket on the back of the case. At the bottom of the main chamber is a padded divider fixed with velcro, so you can have either one large interior chamber, or two smaller ones. I found that I can use this lower compartment to store whichever lens I'm not currently using.
I use a Canon EOS 1000D + 18-55 IS Lens with a spare Tamron 70-300mm f4/5.6 lens. The case is big enough to fit the camera with either lens attached, so I can either store the 70-300mm lens in the bottom compartment and the 18-55mm lens attached to the camera in the main compartment; or keep the 18-55mm lens in the bottom and the 70-300mm lens with camera in the main compartment. However, if I'm storing the 18-55 in the bottom, there isn't enough room to leave the lens hood on the 70-300mm lens, and I need to minimise its size by adjusting zoom and focus to fit it in, but that's no great disadvantage.
If I want to leave the lens hood on the 70-300mm lens, I can keep the 18-55mm lens in the front pocket and open up the divider so that the main storage compartment is maximised and the camera fits in with 70-300mm lens plus hood.
The only downside is that the case is quite bulky, and it could have been a bit more compact as there's room to spare even with the 18-55mm lens in the bottom of the case and the SLR plus 70-300mm lens in the top bit. The overall result is very good and gives a lot of flexibility and I didn't need to order a separate lens case after all.