I've already posted this a couple times, but screw it- here it is again. Just as an aside maybe you could do a little more searching before bringing this repeated thread up. Anyway, I've included some biochem, anatomy, and physics notes that I took a little while back. Calculations, equations, chemical structures- all easy once you get used to it. On to my opinion...
I LOVE my iPad mini. I have all my college textbooks on it (purchased via Aamzon or scanned), take all my notes on it, and game and surf on it when I'm bored. Ok, so the screen isn't Retina, but it's still a great screen. I mirror what a bunch of people have already said: readability of textbooks is fine, I don't have to "constantly zoom in and out" like other "users" do. I posit that these "users" probably don't have minis, are hard of seeing (not being rude), or are whiners (being slightly rude). I user PDF Expert to keep all my books and school material (syllabi, ppts which I've converted to PDF, etc.) on my mini with PDF Expert's excellent Dropbox syncing (other PDF software also has Dropbox syncing). I use the new Jot Pro by Adonit (with sound dampening tip purchased from Amazon) to take ALL my class notes. I don't use paper at all anymore, and by following Lifehacker's posts on keeping your computer linked to Dropbox, whenever I'm on my Retina Macbook Pro, all my files are synced in the background.
iPad mini + the Jot Pro + Lifehacker's Dropbox info + PDF Expert = Awesome.
BTW, I have the 16GB mini wifi, as I use my iPhone's wifi hotspot when I'm not at home or school, which both have wifi. Also, I can even fit the iPad mini in the front pocket of my jeans! I wear Express Kingston classic straight leg jeans- so they're not skinny jeans, nor are they baggy jeans.
Personally, I've used the iPad 4 and I just think it's WAY too bulky and heavy. The mini is the iPad Apple should've released from the beginning.
From someone who uses his mini for at least 5 hours a day- many times 7-10 hours a day, I am super happy I bought it! Hope this help dude. You can PM me if you have any other questions.
16GB iPad Mini Wifi = Awesome