Ah, yes, the coating. I'm not sure it actually interferes that much , but I'll ask a friend (he developed it)

I had weird data issues, but I was only sending sms and mms to twitter (for my liveblog) I had great connection from, say, Conops, in the bowels of the hyatt, but standing on the street between the marriott and hyatt was a no-go. And Usually the Hilton was ok.

my wife has a smartphone, we had good data speeds up in the 24th floor of the marriott (which is the lowest we've ever been, and we want to be back in at least the 30s in future) all weekend, but we were also on the north side of the hotel, Who knows though, it's been 12+ years since my last class on cellular signals