The headline's a little misleading, because this is the ONLY large form factor at this price point.
Pros - Half the price of other 10" e-readers - Supports more formats (26) than either Kobo or Kindle - Standalone Linux kernel isn't tied to DRM sources; in fact you can use it without a wifi connection - microSD slot, you can put another 128GB of your library into the reader - Not tied to DRM, can run completely without a network connection
Cons - 150ppi is lower than Kobo's 227ppi and Kindles 300ppi - No audio book support - Note taking support is extremely basic
It's $300 ($270 as a I write this) for a 9.7" ereader. The only real competition for a 10" form factor are the Kobo Elipsa at $499, and the Kindle Scribe at $509.
Given that it's essentially half the price of the others, there are some compromises. First, it's 150ppi resolution, rather than 277ppi (Kobo) or 300ppi (Kindle). Whether that matters will depend on what you do with it. And unlike the Elipsa and Scribe, it's also only an ereader. It doesn't support audio books, and although there is some basic note-taking ability, it's primitive compared to the others.
If you read scientific papers in PDF, and you want to zoom in to graphics, it won't be anywhere near as good as the Scribe is. And if you use really small fonts, they're going to be harder to read. But if you use it to read epub or mobi ebooks, the 150ppi is perfectly fine.
If you're really fussy, you may notice that the backlight is not distributed uniformly over the screen, but that's really only noticeable in very low light conditions.
TLDR: If you're considering it because you have poor vision and want a larger screen than the normal 6" ereader, it's great. If you want to use it for PDF presentation, consider the Elipsa or the Scribe. But if you need to zoom in to PDFs, listen to audio books, or mark up your books and take extensive notes, look elsewhere.