I've tried a few Amazon devices, and came away relatively disappointed, even knowing the limitations up front. The first was a Fire TV Stick. The interface is heavily Amazon-centric, which I knew going in. I didn't realize how frustrating and non-intuitive it would be to use other services, however. It was one of those things that I thought I could get used to. I paid half price for it during their opening promo a number of years ago; I probably won't buy one again.
Amazon had a super low price on their 7" Fire tablets back in the fall. We bought two for our kids...something like $30 each. How bad can they be, right? Physically, I'm impressed with the build quality. The plastic casing feels cheap, but has proven to be very durable. The screen, as indicated by Supton, is notably poor in resolution (and very prone to reflection). The most frustrating part, though, noted here by others and similar to the Fire TV Stick, is how Amazon-facing the user experience really is. You can't install Chrome or YouTube on it -- not without either trying to side-load the apps or rooting the device to install another shell or launcher. So synchronization with your bookmarks in Chrome won't be straight-forward. If you use Firefox, it may be okay -- I'm not sure if Firefox is in the Amazon App Store. These tablets, again, were a case where I read a lot of reviews and thought I could get used to them, but I cannot. The kids never use them. They just sit on the counter in our electronics "basket".
Given a general use case, I would recommend against Amazon hardware. Not because it's poor in quality (it usually isn't), but because the low purchase price is subsidized by the delivery of Amazon-centric content to the exclusion of other stuff. I'm not upset that it's that way (they have every right to make a buck), but the tradeoff is not what I expected, so I probably wouldn't do it again. If buying ONLY to surf the web or read Amazon e-books or watch Amazon streaming, I think the ratio of what you get to do for the price paid is much more attractive.