The first thing that I noticed when installing the case is that it is a lot more rigid than it looks and required a fair amount of force to install and remove from the iPhone. Because of this, it will bubble most if not all screen shields. I don't use a screen shield, so no worries for me. The case extends over the screen with a nice amount of lip to protect your phone when it is dropped and also provides sufficient lay on the table design.
In the packaging, you'll find replacement corner bumpers in different colors (based upon which color your case is). You can see all of the color combinations on the website. The bumper pieces are easily swappable by pushing them through the case from the outside. They are small, soft rubber pieces which brings me to my first complaint about this case. The bumper pieces hold pocket lint like crazy as I found out when I took my phone out of my pocket when I got to work today.
Ballistic did a great job with the cutouts for the controls. The cutout for the headphone jack is very large and will fit almost all headphone plugs. On top of the case, you'll see the on/off switch is covered but unfortunately provides very poor feedback i.e. you have to press very hard to get the switch to activate. Along the bottom of the case, there are 3 separate cutouts for the speaker, microphone and 30 pin dock connector. The 30 pin cutout is very large and shouldn't pose any issues with aftermarket cables. Along the left side there is an oversized cutout for the silent switch which makes the case compatible with all versions of the iPhone 4/4S. The volume buttons are also covered but fortunately these provide great feedback and didn't pose any issues.
Overall, Ballistic did a pretty good job at creating a slim and protective case that you can use on a daily basis versus using a gigantic Otterbox. I've noticed that a LOT of people buy the Otterbox Defender and i'm not so sure why when they can buy a nice slim case like this one. The Ballistic Lifestyle smooth is available in 6 vibrant colors and sells for $29.99.