I have been using iPads since the second generation was released. I have found in my Apple opinion, purchasing the second generation or later of any of their products is truly the best practice. I stuck with the iPad 2 until this year when I purchased the iPad Air 2. Which I love! Going from the 2 up to the Air 2 was like night and day when it came to functionality, speed, weight and security. The Retina Display is gorgeous. The speed bump is ridiculous. The weight is so noticeable that you would not even think you are using the same machine. Finally the finger scanner is not without its flaws, but the ease at which one can unlock the device without a passcode is wonderful.
I use the iPad everyday in class. I complete my daily lesson plans on it using the planbook.com app and website. I use Splashtop to easily access my Smartboard and desktop computer without having to be in my classroom. Accessing the districts web-based grade-book and attendance is flawless.
I count on my iPad each day I enter the class and would recommend it to any educator who wants to streamline their classrooms and life.