"Difficult to use" is subjective, so I'm not touching that one..
Consider checking out out the *new* nikon D3100 -> http://www.nikonusa.com/Find-Your-Ni...472/D3100.html
At a quick glance the D5000 (http://www.nikonusa.com/Find-Your-Ni...452/D5000.html
) only does 720p video with NO auto-focus while the D3100 does 1080 WITH auto-focus!! That alone give the D3100 an advantage in the video department and it's only $70 more.
I'm not up to speed on the Sony... My only concern is that if you're going to get serious about taking photos then Nikon definitely has a better (and yes more expensive) selection of lenses to choose from. This is something to consider for re-sale value down the road if things don't work out.