You can't see shit on an iPad outdoors in the sun. The glare is ridiculous. Also, I read in bed at night and the backlit iPad keeps me awake longer (computer lighting fools your body into thinking it's still daytime or something which I've found to be really true, personally). If I'm not reading a physical book, I read Kindle at night before sleep, never iPad.
I have an original iPad and have zero interest in upgrading right now. I don't need facetime or a camera on my iPad and for what I use it for, the processor is fast enough.