The Amazon Kindle Fire HD10 (2017) is the high-end tablet of their line. The hardware is mediocre and the software is quite bad. I do not recommend you purchase this or any other Fire tablet... unless you have some very specific requirements.
Let's consider the negatives, first.
Bootloader is locked
Having a locked bootloader means that you can't replace the OS with a sane one. If you could do that, then all other software problems could be overcome by a slightly technical person. (If you can follow directions well enough, there are good guides for most systems to walk you right through the process of installing a sane Android OS.)
Hardware is not fast
The Fire HD10 has a MediaTek MT8173 CPU, which offers 2 fast cores and 2 slow cores (for power saving). The fast cores are not as fast as a 2018 phone's slow cores. This is not a device that can play high-end games. It is just about suitable for watching HD video.
Operating System is owned by Amazon Marketing
The marketing divisions of Amazon, Facebook, Google and Microsoft are descended from the Sirius Cybernetics Corporation's Marketing Division. The OS assumes that since you gave Amazon money once in order to buy the tablet, you must want to give Amazon all your personal information and buy things exclusively from Amazon in the future. It implements ridiculous locks to make the process of customizing the tablet as difficult as possible. For example, Android devices have a replaceable launcher. That's the program that runs when you tap the Home button, and provides access to the other installed applications. FireOS doesn't want you to do that, so they half-assed a lock to prevent installing a different launcher.
Rooting is painful
On sane Android devices, here is the procedure to get root privileges:
- Tap the serial number 7 times to open developer mode.
- Set up USB debugging mode.
- Reboot to recovery.
- Use the USB debugging link to install a superuser package.
- Reboot to normal.
This one isn't sane; it's more like an Apple IOS device, where you need to look for a hole in the operating system that you can exploit to temporarily get root privileges so that you can install your superuser app. If you are thinking that the presence of such a hole means that other programs can also gain root, you are correct. This just shows the lack of attention to your security on Amazon's part.
Considerations which might make this worth buying
The Fire HD10 (2017) lists at $150 and is frequently on sale for $120.
The 10" screen is 1920x1200, which makes it adequate for my intended usage. The combination of this price and this screen makes it worth buying... for me.
The process to root the phone is arduous, but it does exist. I don't like having computing devices in my house that someone else owns.
In addition to a reasonable built-in storage, it has a microSD slot that can handle a 128GB card, and might be able to handle a 256GB card. That means you can bring enough local media to keep yourself entertained for a while.
Why I bought it
After rooting it, destroying most of the Amazon ecosystem and dashing the dreams of their marketing division, I plan to load it up with comics and books to read. Comics demand a fairly large, fairly high-resolution screen, and they want lots of storage space, but they don't need much else. Showing one full page of comics every five to fifty seconds just isn't taxing to any CPU that can decode a 1080P video frame 30-60 times per second.
What you should buy
If you are non-technical, get an Apple iPad mini, and accept that you will be shown ads and not have much control over your life. If you want a general-purpose Android tablet that you can control, the Samsung Galaxy Tab A 10.1 (2016) is faster, has a similar screen, microSD slot, and is better built. It's also more expensive.
If you are want to spend as little money as possible on a comics-reader, are prepared to figure out that 18.104.22.168 has the Dirty COW (CVE-2016-5195) vulnerability while 22.214.171.124 does not... sure, go ahead and buy this. Don't say I didn't warn you.