Nikon doesn't make a bad DSLR, they just vary in their design to target specific types of user. The D5100 shares much of the D7000's technology and should produce similar image quality but the body style and menu interface is more suited to the less advanced user (ie those seeking a lot of customisation and fine tuning options). It does however have an articulated LCD screen, which the D7000 does not have.
Also, as you said, you'll need AF-S lenses to get autofocus.