Gigaom wrote about slowing iPad sales.

Expecting iPad sales growth to mirror that of the iPhone, which is still on a relatively stronger upward direction, is unreasonable for a number of reasons. First: phones are far more a communications necessity than tablets are, at least for now. That’s why 2013 saw nearly one billion smartphones sold with expectations of another 1.2 billion more in 2014. By comparison, last year the tablet market only topped 195.3 million units, per Gartner.

Different upgrade cycles:

Give someone 18 months or so with a phone: They’re ready to upgrade and a carrier is very likely to help them do so with financial incentives. However, tablets in this regard are more like traditional computers: They’re going to last longer for most people. For one thing, they’re typically not subsidized so an iPad buyer is looking at an up-front investment of $499 or so (less for an iPad mini or older iPad, of course). Add a cellular radio and that investment jumps by $130, making the base iPad Air 26 percent more expensive. That’s no small price to pay and it’s one that makes it more likely that a consumer would keep the device just a little longer instead of buying the next shiny tablet that comes along.