I can't use an expensive smartphone without having a decent case. It just worries me too much. For my Blackberry Bold I bought an Otterbox Impact case and loved it, so when I got my Inspire 4G I wanted something made by Otterbox, but tougher than the Impact series because I was afraid the giant glass screen would be easy to break if I dropped it. So, that meant buying the Otterbox Commuter case for the Desire HD, which is compatible with the Inspire.
The Commuter series has two parts, a soft rubber layer and a hard case that goes over it. The rubber layer protects the phone by giving it some bounce in a drop, deflecting some force away from the phone. The hard case makes it easy to take out of a pocket and keeps the rubber layer from becoming a lint magnet, as well as protecting the phone. It comes with a screen protector, which I actually put on upside down by mistake, but it still covers the screen just fine.
It's definitely a nicer product than the Impact series, the additional hard outer layer prevents the rubber layer from getting loose and wobbly over time, and also keeps it from getting covered in pocket lint. I haven't dropped my phone yet, so I haven't had any experience with how well the Commuter deflects the impact of hitting the ground away from the phone, but since I did drop my Blackberry and this case is tougher than the Impact case I had for that phone I expect it to hold up well.
Overall I'm very happy with the Commuter case. It does add some heft to the phone but the protection it provides is worth it to me, since I'm not putting up with insurance on this phone.