Apple released the iPad as a device aimed at the living room.  I agreed with this position and fully expected to use the device while sitting on the sofa, casually watching TV, to check email, Facebook, surf the web etc.  However … I actually have found that I reach for my iPhone when I’m in these situations.

Why?  I think it’s actually pretty simple (and perhaps lazy).  I’d rather grab a device that I can operate using one hand.  The iPad is a 2 hand device, and for something as simple as checking email, twitter, or Facebook, I’ll simply grab my phone.  For doing any surfing that’s more involved … such as online shopping … I’ll grab the laptop.  It’s just too painful to type anything more than 2 sentences on the iPad.
In all honesty, the only place the iPad’s taken over for me is inside an airplane.