People who say the bumper will offer no protection are missing common sense.
The bumper will protect your iPhone in almost any situation. Drop the phone one of the sides or corners first? Without a bumper your screen is probably gonna crack, if not, then at the least you're getting a scratch on the stainless steel band. With the bumper the band will be safe and the glass has a much higher chance of not breaking
Drop the phone flat? With out the bumper, good chance the glass will crack, and even more so now that both sides are glass. With the the bumper being raised a little above the glass, you are good. No matter how the phone drops face or back first, the bumper will make contact on the ground first and will keep the glass off the ground.
So basically, no matter how you drop this phone, there's no way for any of the glass or the stainless steel band to make contact with the ground. Thats pretty good protection if you ask me. The only way the bumper wont help you, is if you drop the phone on the corner of something or an uneven surface like some rocks, but that's a very slim chance.
Now the people who prefer to buy full body cases or screen shields are the suckers. A full body case is going to cover up the great design of the phone and only going to offer you the little extra protection in the case of dropping the phone on some rocks. Not a worthy trade off at all.
And if there's one thing you don't need to worry about with the iPhone it's the screen scratching. I've had an iPhone every day of my life since the launch of the first gen, and I've never gotten a scratch on the screen. I don't baby it either. As long as you don't take it with you to the beach and throw it in the sand, you're not scratching the screen. ifixit said they took a screwdriver and razorblades to this thing and couldn't scratch it. I'm sorry but people who buy screen shields to protect it from scratches are the biggest suckers of all.
To summarize all this, I think the bumper case is the perfect solution. It doesn't detract from the aesthetics of the phone, offers great protection in almost every situation, and leaves both glass sides free to see and touch.
I'm willing to bet that an iPhone 4 kept in a bumper case for a year will still look pristine and brand new when taken out of the bumper.