I don't believe the backhaul has been deployed across the network yet, I thought it was due sometime in March?
Although the phone shows H+ I believe it is still 3G in most areas
I tested it in the AT&T store this morning using the FCC app. The first test my iPhone 4 was faster and the second test the Inspire was faster. Both were close though. I guess that means there was no 4g going on even though the Inspire showed the H+ icon. I was quite disappointed.