There's a thread here that'll give you some feedback -
https://forums.macrumors.com/threads/540157/
There's been quite a few people here commenting on these covers, so it would probably be best doing a search.
Generally, feedback about this make is very positive.
Personally, I prefer the feel of typing using these covers, rather than the nake keyboard. Also, they dampen the sound of keys being depressed quite noticeably, which is handy if you're in quiet public areas and wish to be considerate.
its ok i guess
i think it would only be good if you eat over your keyboard a lot...or if you hands sweat when you type lol
in that case...thats just gross
No matter if you've just washed your hands, when your skin comes into contact with something, oil to a degree will be left behind. When a laptop is closed, oil that has been transferred from your fingertips to the keys, can then be then transferred onto the screen causing it stain. Of course, one can could get around this problem by wearing gloves...
Although you might not be mucky, those around you maybe - in the above link, one poster reports his MB being protected when his baby decided to throw a drink.