Apple's much anticipated entry into the wearable market faces one big challenge—the wearable market itself.
Mike Prospero, reviews editor at Tom's Guide, told CNBC that the market seemed "fairly tepid," and it's already rife with competition. Only about 1 million smartwatches has been sold so far, he added.
Smartwatches are "all sort of incomplete at the moment," said Prospero, who recently reviewed the most popular ones. "None really last more than a day on a charge except for maybe the Pebble, which is a big consideration when you're carrying something around."