The Amazon Fire 7 gets amazing reviews in the technical press. If you need a new tablet (and don't want to fork out mega-bucks for an iPad) it's an excellent choice.
However, as Bednobs has indicated, 8GB isn't a lot of storage space. I'd recommend paying the extra tenner for the 16GB model.
Be aware that you won't the Google Play apps store as the Fire is a heavily modified version of Android. You can side load it but a lot of apps still won't install properly.
What do you want to do with it?
Not on a Fire 7 you won't! (8 GB and 16 GB are the only two options available). Moving up to the Fire HD 8 offers a choice of 16 GB or 32 GB but at prices of £49.99 or £69.99 respectively.