I have recently purchased this item. Before I did buy it, I did have doubts about whether it would affect typing, and I didn't think the feel of the keyboard would be quite the same. Although having thought that, when I first used this product, all my doubts were set aside.
This item works fantasticly well on both of these fronts. In terms of feel, there is almost no difference between not having the protector on, and having it on. Apart from a slight rubbery feel, although this is a plus point as it gives off more grip. Therefore you have less typos. Fitting the protector couldn't be easier, even if you know nothing about what you need to do. You still couldn't go wrong. To install it, simply align it with your keyboard and push in. That was hard wasn't it :). So overall, no faults what so ever in terms of feel and practicality. The protector won't affect your typing at all.
Reasons for Getting one
Well there is one obvious one, and this is protecting your laptop from getting ruined. Keyboards aren't as bad when they get liquid spilt on them as they can be replaced relatively cheaply. But laptops are the very opposite end of the story. The chances are that the only gaps you have in the front of your laptop are the spaces between the keys. This protector is completely watertight and therefore protects your laptop from spilt drinks etc. The second useful thing about the protector is that you can't loose stuff underneath your keys. If you have a laptop, I am sure you must have spilt a crumb etc. underneath a key and from then on that key hasn't typed the same. Usefully, the protector also stops any dirt from going underneath your keys. Prices will vary for the keyboard protectors, the brand mentioned in this review are slightly more expensive than other models. Although you have to remember that they are custom made for certain keyboards. Although I recommend buying a cheaper version. Just do a search on ebay for "keyboard", choose the computer accessories category. Then order the results in terms of lowest price first. I managed to pick up one for 1p by doing this. I have had that 1p keyboard protector for 2 months now and it is absolutely perfect. In fact I am using at the moment. So basically, just don't buy the branded stuff, it is massively overpriced.
So overall, you can either pay a little for a keyboard protector, or a lot for a new laptop. Your choice!