Like every other electronic device apart from those using monochromatic e-paper, trying to use it in DIRECT sunlight will be highly problematic. Should work just fine under a shady tree, however.
For myself, since I use my iPad in a lot of public spaces where the light sources or daylight can cause glare, I've opted to use the Moshi iVisor AG screen protector, which gives my iPad Air 2 a matte finish and GREATLY reduces the glare from direct sunlight.
Here's a photo from a comparison of the matte (AG) iVisor and the perfectly clear (XT) iVisor that will really give you a very clear picture of the important difference it can make if you plan on using it in direct sunlight a lot:
Same iPad with the two different screen protectors on. The XT on the right is "invisible" by which I mean it is as reflective as the iPad would be without any screen protector on.
Bottom line: no notebook, tablet, or phone for that matter works well in direct sunlight. You'll want to rethink that strategy, or get an e-paper Kindle, if being able to read in direct sunlight is your priority.
