Nexus 7 vs iPad mini advice on screen dimensions

I am considering buying either the nexus 7 or the ipad mini. My primary consideration however is the screen size not the dpi. The nexus 7 is 16:9 while the ipad mini is 4:3. I am purchasing these primarily to read pdf textbooks. Does anyone have experience reading my biochem and microbiology textbooks using the nexus 7? Does the screen look too thin? I have looked at the ipad mini at the apple store and it seems ok. I just want a comparison to the nexus 7 before I pull the purchase trigger!

Any advice on experience is appreciated!