For what it is worth, we have an iPhone 4 (not S) and a 3GS and they both connect fine and stay connected.  Both are running 5.0.1.  But in the past they wouldn't see the microcell without going in and out of airplane mode,  and then suddenly they would.

My big problem is the delay on dialing out, for which there is 22 page thread.

The microcell is a majorly buggy device.