I have a Bumper and my iPhone 4 is working beautifully. My wife did not want a Bumper (she's waiting for others to ship) and she hasn't had any problems in casual use. Personally, I like the feel of the iPhone better with the Bumper than without. I'll be watching what Vaja Cases produces. The case I got from them for my 3G was the best, most striking case I've ever had.