These are an excellent buy. They are very clear and reasonably bright at 8x magnification; however, as you would expect, things get rather darker and a bit less sharp as the magnification is increased. By the time you get to 21x the image is less sharp, but then it is hard to hold still at that magnification anyway.
They are really nice to use: feel better made than you could expect at the price, and focusing is smooth and easy. They are nice and compact, the sort of thing you could easily keep in your car, rucksack or wherever and thus score over more expensive and larger binoculars in that you might well have these with you when you actually need them, which is always more useful than the fine pair you have left at home.
They come with a useful pouch which would attach to your belt (don't think I would) or rucksack strap perhaps.
I think they are a good balance between being too cheap and cheerful (I have a pair like that and wish I hadn't...) and so valuable that you worry about getting them wet, nicked or lost.
In summary, I'm very pleased with them and recommend them, but don't get too excited about the 21x end of the scale: they are much nicer at 8x.