The adverts appear only when the screen is locked - as soon as the device is in use, no adverts!
But you still watch adverts that Amazon want you to see, even if its only for a second, no matter if you want to or not. The tenner they knock off the price is something they think is worth paying.
The Fire is a cheap Android tablet - and thats totally fine. In fact its sold along the lines of the razorblade model - the razor is cheap, but the blades are more pricey. For my kids, totally fine, and excellent value for money.
However, try using it in the same way as a normal Android tablet, and perhaps download apps from the Google apps store. Not going to happen, unless you tinker with it -
http://www.teleread.cohttp://kindle...-to-the-50-fire-tablet-and-what-happens-next/ . Want Chrome as your browser, rather than Silk? Again - possible, but a hassle. The device wants you to go to Amazon for apps, film, books, etc. Thats OK, but nobody should buy one expecting otherwise.
The Fire is very cheap for what it does, and thats understandable. But its not a Galaxy Tab or an Ipad - they are generally more powerful, with a wider range of apps. Its not fair on either to compare them with each other as direct rivals. So if I was looking for a cheap tablet that does the job, the Fire would do nicely. But if I wanted a bit more flexibility, without the need to go under the bonnet, then I'd chose something else. You pays your money, you make your choice.