I bought the JamJacket because I wanted something that fit the iPhone snugly and protected it very well, covering the black area around the speaker and the home button, but not the screen. This is the only case fitting that description at the AT&T store. I'm not concerned with how it looks in the case as much as I am protection. This thing has kept my iPhone scratch-free, and I paid very close attention the first few days to make sure it was not scratching the bezel or back.
I used a fresh razorblade of the box-cutter variety to carefuly slice the earphone protrusion off so close that the back was almost completely even all the way across. Doing this still left an ugly scar on the back of the case, but as I said, I'm more interested in having maximum protection while still having the screen open than I am visual appeal. After experimenting with the compartment a little bit, I found that it did not hold the headset tightly enough for my taste, it was too flimsy and not designed well for carrying the headphones around in your pocket all day every day. If you're a woman that carries a purse or bag, or a student with a backpack, or you like to use your iPhone as an ipod all the time, then you will probably enjoy that feature. I just like everything to fit nice and snug because I carry mine around in my pocket. The extra protrustion/weight really wasn't bad if it was useful, just once I found that I wouldn't be able to carry my headphones around comfortably on this thing every day without them falling out or becoming loose, I decided to cut it off to slim it down.
iSkin is releasing a very nice looking case that fits my needs, and the contour iSee as well as another hard shell case on Apple's website would fit my needs and I will be ordering one soon. In the mean time, this case provides excellent protection, and it doesn't slip while gripping it at all, except a tiny bit around the home button and speaker, which is acceptable because when you are gripping it it does not slip, that is just a purely cosmetic thing. Like I said, I want my case to be like a part of the iPhone, very secure and snug, maximum protection, low profile, doesn't cover the screen. The JamJacket does that pretty darn well. With the iPhone's sturdy construction and density, the silicon JamJacket just makes it almost invulnerable to everyday scratches and dints, and would almost certainly protect it from a short fall, like when you hop out of the car with the phone in your lap. When you drop it on the table it just makes this nice little thud, and doesn't bounce at all, that is reassuring. Not the most well designed case, but I definitely do not regret buying it at all.
I also bought the little crystal case which they have at AT&T stores, and I love the way it looks, it offers excellent protection to the back and bezel, but I think it might scratch the chrome bezel a little bit when there's debris in it, which is unacceptable. Furthermore, it does not protect the black area around the home button and speaker at all. I also feel that if it were dropped from any distance onto hard concrete or flooring, due to the thin plastic nature of the case, it would crack open. I could be wrong, but I won't risk it. It looks pretty sexy, though, which is the only thing it really has going for it.