Same goes for the iPhone 4...
We had one user get through 4 iPhone 4s (plural, not 4S) in May and June. Crap call quality, dead batteries, poor WiFi (under 2M) and BlueTooth reception (under 10cm).
I'm no fan of the Lumina, but Nokia aren't the only ones with quality control problems.
I think, from the 5 iPhone users we had last year, we have had 8 replacement 3GS phones and now the 4 iPhone 4 phones.
Okay, that is only anecdotal, not representative of the whole production run, but it is "funny", that such a large number of dud phones turn up over the period of a year in one organisation.
I think one of our "big" problems with the iPhone was one user who actually uses it as a phone, with up to 4 hours talk time a day. The iPhones don't seem to like that sort of "abuse", they much rather sit in the pocket and do the odd bit of surfing or Angry Birds, but they seem to really hate being used to make calls!