Different strokes for different folks. I agree that there are better tablets out there than the Fire HD 10. But, I have a 7th generation tablet and have been very happy with it. I put the Play Store on it and nearly all my apps have played nice with it. Watching videos, internet browsing, and running a couple of reference apps works just fine. The screen is bright and the colors are vivid. I use it every day for an hour or two.
I wish it would do split screen and the screen does have glare issues in certain lighting conditions, but for a $100, it is a fantastic deal. (I did pay $15 to get rid of lockscreen ads) I have an Apple mini-pad but I nearly always opt to use the Fire HD for screen size. I have just purchased a new one for my wife who also has a mini-pad. If she doesn't like it, I will be more than happy to take it for myself.
So I guess it just depends on what you are planning on using the device for as to whether it is a piece of junk or one of the best bargains online.