I had it and tried to make it work, but ended up returning. It caused problems with my network, basically stopping traffic while I was on a call. The coverage also wouldn't cover my whole house, so while the basement now has 5 bars, I couldn't get anything in my livingroom.

The microcell was just powerful enough that the phone wouldn't drop the connection and use the AT&T tower. I couldn't make calls now from some of the rooms which previously had service from the big towers. They do advertise that it covers 3,000 sq ft and our house is 6,100.

Moving to iPhone 4 improved my normal reception to the point that we how have a signal from the basement, so I don't miss the microcell.