Caravan Front cover

The one that you put on the front for when travelling.

What if any are the pro's and con's of these items?  Am tempted to buy one simply to protect the front of the van from stone chips and becoming a mosquito/insect cemetery. 

Are they easy to fit? does they affect wind resistance thus fuel consumption and do the straps that fit it mar the van when flailing in the wind etc?

Thankyou!